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## Is the Home Run Derby bad for baseball?

Posted by Andy on July 8, 2010

The Home Run Derby, played the day before the All-Star game, has become a favorite event for many baseball fans, especially younger ones. Even I enjoyed it the first year or two. In recent years, however, there has been significant speculation that the players who participate in the event face the possibility of negative impact on their home run production in the second half. Allegedly, the swing typically used in the Derby, an all-out uppercut, is so different from the swing typically used in real games that some players see a second-half power dip due to their swing getting off-kilter.

Let's take a look into the stats and see if this is true...

First I'm going to list some simple data for a subset of players who have participated in the Home Run Derby dating back to its inception in 2000. I chose to look at the two finalists for each Derby, as these players each competed in 3 rounds, taking the most swings.

I have listed the winner of each derby in the table below, followed by the runner-up of each derby in the second table. I listed them separately because it was easier to do in Excel this way, but otherwise I'm treating all of these players the same for the purposes of this study.

For each player, I list their home run and plate appearance totals before the All-Star break in the given year, as well as the same two totals after the break. I then calculate the change in their HR/PA production from before the break to after. (So a positive number means their home run frequency went up, and a negative number means it went down. Keep in mind the changes are based on home run rates, not just raw number of homers.)

Home Run Derby winners:

```		before		after		change
2000	Sosa	23	394	27	311	49%
2001	LGonzlz	35	388	22	340	-28%
2002	Giambi	22	381	19	308	7%
2003	GAndrsn	22	370	7	268	-56%
2004	Tejada	15	353	19	372	20%
2005	Abreu	18	397	6	322	-59%
2006	Howard	28	352	30	352	7%
2007	VGuer	14	368	13	292	17%
2008	Morneau	14	412	9	300	-12%
2009	Fielder	22	387	24	332	27%```

Home Run Derby runners-up:

```		before		after		change
2000	Griffey	28	381	12	250	-35%
2001	Sosa	29	375	35	336	35%
2002	Sosa	28	370	21	296	-6%
2003	Pujols	27	396	16	289	-19%
2004	Berkman	16	365	14	322	-1%
2005	IRodrgz	6	310	8	215	92%
2006	Wright	20	386	6	275	-58%
2007	Rios	17	389	7	322	-50%
2008	Hamiltn	21	425	11	279	-20%
2009	Cruz	22	265	11	250	-47%```

A few observations:

• It appears that none of these players had an injury that caused them to miss significant playing time either before or after the break,which is great. Each guy had a normal season in terms of games played.
• The big increases in terms of HR output after the Derby were for Sosa in 2000 and 2001, Tejada in 2004, Rodriguez in 2005, Guerrero in 2007, and Fielder in 2009.
• The big decreases in terms of HR output after the Derby were for Griffey in 2000, Gonzalez in 2001, Anderson and Pujols in 2003, Abreu in 2005, Wright in 2006, Rios in 2007, Berkman and Hamilton in 2008, and Cruz in 2009.
• Overall, players had an 8.1% decrease in HR output (per plate appearance) after the All-Star break.

A bit more data relative to this last point. Here are the overall MLB numbers for homers before and after the All-Star break:

```	before		after		change
2000	3312	101879	2381	88363	-17%
2001	2983	100819	2475	86142	-3%
2002	2649	99812	2410	86794	5%
2003	3045	108472	2162	78965	-2%
2004	2826	101440	2625	87079	8%
2005	2685	100470	2332	85804	2%
2006	2942	102315	2444	85737	-1%
2007	2589	101588	2368	87010	7%
2008	2803	110115	2075	77499	5%
2009	2707	101597	2335	85463	3%```

Again, that's HR and PA before and after the break, and change in HR rate. For the 10-year period, the total difference is actually zero. If you throw out 2000, where there was a large discrepancy in first-half and second-half homers, there is actually an average increase in HR frequency after the break of about 3%. All in all, this suggests that the 8% drop-off seen among the Derby participants is meaningful, as this is not what happens with the general population of MLB players. Of course, it's also true that the Derby participants are mostly outliers. These are usually guys who hit a well-above-average number of homers before the All-Star break, so the second-half performance may simply be a regression to the mean.

However, looking at the list of names more carefully reveals another pattern. Guys like Sammy Sosa and Ryan Howard have always hit a lot of homers both before and after the All-Star break. (Howard has had a few huge Septembers so far in his career.) It would appear that participation in the Derby didn't affect their swings, but that doesn't mean others were not affected by their own participation. Many of the players who saw a big drop-off in the second half were not typically among the best power hitters in the game. Abreu has topped 25 HR in a season only twice. Anderson has hit under 20 homers in 10 different full seasons. Wright averages 27 HR every 162 games. There is a suggestion, then, that the big-time power hitters are not affected by playing in the Derby but the lesser power guys are.

But is this true? Let's think again about the selection bias for the Home Run Derby. The participants are usually among the HR leaders going into the All-Star break. (The only obvious exception to this among the group of players in this study is Rodriguez in 2005.) If a player happens to have had a really hot first half and then a typical-for-him second half, it may look like he had a big drop-off in his power numbers when in reality what he had was an unusual rise in the first half of one season.

Alex Rios is a good example of this. Let's ignore 2007, the year he played in the Derby. In the rest of his career from 2004-2009, he had 34 homers in 1563 plate appearance in the first halves of each season. In the second halves 2004 to 2009 minus 2007, the numbers were 26 homers and 1233 plate appearances. That is, on average, a 3% drop from first half to second half. (If he'd had one more first-half homer or one fewer second-half homer, his HR frequency would actually have gone up overall from first half to second half, so essentially his production is level between the two halves.) His overall HR rate over these years is one HR every 46.6 plate appearances. In 2007, in the second half, he hit 7 HR in 322 plate appearances. That's one every 46.0 plate appearances, which is identical to his performance every other year of his career. In the first half on 2007, he hit 17 HR in 389 plate appearances, or one HR every 22.9 plate appearances. That performance, his first-half performance in 2007, is the aberration. That's why he was selected to the Home Run Derby in the first place, and that's why his numbers seem to have suffered after the break--but in reality all they did was go back to normal.

Obviously, the effect of participating in the Derby varies from player to player and year to year. Many other factors, including nagging minor injuries and strength of pitching faced, can affect home run numbers before and after the All-Star break. Overall, though, it seems that since the players with the biggest second-half power outages seem mainly to be the players with overall lower HR rates in their careers, I believe the effect is primarily a selection bias among the players chosen to participate in the event.

### 30 Responses to “Is the Home Run Derby bad for baseball?”

1. Frank Clingenpeel Says:

Much of the variation in home run output after the All-Star break can be attributed to simple attrition. Bodies -- even those of players drawing seven-figure salaries -- have a tendency to wear down as the season goes on; injuries increase, and fatigue of course adds to that factor. Perhaps a better way of analysing this would be to assess the percentage of games played before the All Star break as opposed to after it. I believe that it would show some significant variations, but I am not computer-savvy enough to figure out how to set up such a chart. Any suggestions?

2. Shaun Says:

Well, I believe the Home run derby is a very fun event for most fans, but some of the managers, general mangers of MLB believe that the Home run derby is not a very good idea. I believe that there are positives to the Home run derby. But there is also negatives. As you can see from the stats, most people who participate in the derby are not very good in second half. Have you ever found any derby winner that actually succeeded in the second half? Well, look at 2000 Home run derby winner Sammy Sosa, he hit 23 home runs in the first half of the season and then hitting 27 home runs in the second half. In 2009, Prince fielder won the home run derby, he hit 22 home runs in the first half, then hitting 24 home runs in the second half. I do admit that the home run derby has cooled of some players for the second half. Like 2005 winner Bobby Abreu. In the first half of the season, Abreu hit 18 home runs then taking a real slide by hitting only 8 home runs in the second half. In conclusion, I believe that the home run derby can be a bad thing or a good thing. I believe it can either help your hitting or really put down your hitting, but still, the home run derby is a fan favorite!

3. Tom Says:

Andy, nice analysis. Would you like to stick your neck out and predict which players will have regressive slumps that they'll blame on the Derby this year?

4. Andy Says:

Frank, the data is normalized by plate appearances so games played does not factor in. Moreover the data for the overall league performance does not show a systematic decrease in homers in the second half.

5. Andy Says:

Tom, funny you should ask. It was Robinson Cano's inclusion that made me want to look at this but by the time I wrote it the Yankees had withdrawn him from the event. He's the classic type of guy I'd expect to qualify--my sense without looking at the numbers is that his HR rate in the first half this year is higher than his norm, hence the invitation to participate.

How many people even remembered that Alex Rios participated? After the fact it seems quite odd.

6. Danny Says:

Great points here. I wrote about this subject yesterday, before Robinson Cano pulled out last night. That was disappointing. http://blog.thesportsnook.com/2010/07/remember-when-the-home-run-derby-was-no-big-deal/

We live in a weird era where the risk of injury comes first, even if there's no real evidence and validity to that argument. But how can you fight it, yknow? It's the responsible thing to do...

7. Bryan Mueller Says:

I would love to see Ichiro in a home run derby. People wouldn't have to worry as much about trailing second-half home run totals. I have never seen Ichiro take BP, but I read in an article a few months back (Baseball Digest I think) that he can put on quite the show during batting practice. Got me thinking...which unconventional hitter (or pitcher) would you guys like to see in a HR derby?

8. Andy Says:

Zambrano and Owings would be cool.

9. Zachary Says:

This is a great entry. I love the in-depth analysis!

10. Ellis Says:

I just can't imagine that a professional baseball player would significantly damage his swing for half of a season by participating in a home run derby. It's like saying that a player's swing will fall apart if he plays a round of golf; I think any major leaguer can adjust back to his standard swing.

11. Andy Says:

I agree with you Ellis, but many folks (including baseball people) think the swing-ruining phenomenon is real. See this recent article for example (see the comments):

http://www.nydailynews.com/blogs/yankees/2010/07/sources-cano-pulls-out-of-home.html

12. Andy Says:

http://blog.cleveland.com/sports/2008/07/indians_sizemore_to_compete_in.html

http://www.nj.com/yankees/index.ssf/2010/07/should_the_yankees_keep_robins.html
"He was repeating a long-held belief that the Home Run Derby could damage Cano’s swing for the second half."

13. Andy Says:

David Wright

2004-2009, ignoring 2006.
First halves: 49 HR in 1582 PAs (one every 32.3 PA)
Second halves: 65 HR in 1472 PAs (one every 22.6 PA)

In 2006, his derby year:
First half: 20 HR in 386 PAs (one every 19.3 PA)
Second half: 6 HR in 275 PAs (one every 45.8 PA)

So Wright has traditionally been a better HR hitter in the second half, something that doesn't usually hold up over a player's entire career. In 2006, he had TWO aberrations. His first half was by far the best HR-hitting streak in his career, hitting one every 19 plate appearances, and his second half was by far the worst HR-hitting streak. It's possible that the HR Derby had an effect, but my point is that the magnitude of the effect is not as large as some people think, given how much faster he hit HR in the first half compared to the rest of his career.

14. Andy Says:

Bobby Abreu

1996-2009, ignoring 2005.
First halves: 116 HR in 4193 PAs (one every 36.1 PA)
Second halves: 116 HR in 3562 PAs (one every 30.7 PA)

In 2005, his derby year:
First half: 18 HR in 397 PAs (one every 22.1 PA)
Second half: 6 HR in 322 PAs (one every 53.7 PA)

This is the same story as Wright. Yes, his second half in 2005 was bad compared to his career averages. But his first half was also amazing compared to his career averages, artificially inflating the possible effect of the HR Derby.

15. James I. Says:

I don't really understand your percentage change numbers. On first glance, they don't make sense. Regarding tables, you should always leave in labels, and not just leave unlabeled data in columns.

Most importantly, a very basic tenet of all statistical studies is to NEVER just "throw out" outliers (as you did with the 2000 homer numbers when looking at overall homer rates). Often there is something very interesing going on with outliers, and they always deserve close inspection. Only when one can elaborate exactly why one should ignore an outlier should this be done.

Throwing out outliers is just a way of hiding flaws with one's theory. Don't do it.

As a different kind of example, if one were to look at a table or chart of, say, runs created per plate appearance for all players who have had at least 1000 PAs for the years 2001 to present, I know that at least one outlier would be present: Albert Pujols. If one didn't know who it was one might be tempted to just throw out his data point. To do this would be to ignore one of the most interesting players of the last decade. Depending on what you are investigating, it might be warranted to exclude Albert, but in all cases the reason for doing so would need to be carefully explained.

16. Andy Says:

James, I think you're being a bit dramatic. Even with the 2000 data included, the numbers still support my point. I didn't throw it out entirely either.

17. Thomas Says:

This is fantastic Andy! Great work!

18. dukeofflatbush Says:

Wait!
Why was I-rod in the '05 derby?

19. Baseball Reference Blog: Is the Home Run Derby bad for baseball? - MotownSports.com Message Board Says:

[...] [...]

20. Djibouti Says:

Has anyone ever been injured participating in the Home Run Derby? I can't think of anyone off-hand, but it wouldn't surprise me if someone re-aggravated a shoulder injury or something like that.

21. WilsonC Says:

It's common sense that there should be some second half regression, since it's generally guys with big first halves that are chosen. I'm sure that if you were to build a control group of HR derby "snubs" - players who hit a lot of first half HR without participating in the derby - you'd see the same effect, where the true power hitters would usually maintain high power rates and the more ordinary power guys would usually regress.

22. Joe Says:

Yeah, guys selected for the Derby are more likely to have hit a lot of first half homers, so are more likely to naturally hit less in the second half. I think whatever effect there might be is in guys' heads. If you keep hitting homers in the second half, there's no effect. If you don't, it's easy to blame the Derby. It becomes a self-fulfilling prophecy - if you think there's an effect, then there is.

One note, Andy, the Home Run Derby didn't start in 2000, it started in 1985. Maybe it took its current form in 2000, but it's been around a lot longer than that.

Also, Duke, I-Rod was in the 2005 Derby because the game was in Detroit, and at the time, he was the Tigers big star.

23. Zeff Says:

It's not bad for baseball. The way it's run is bad for baseball. Simply put, it's boring with a capital F!There's no reason to not simulate it like a baseball game like the old HR derbies. Strikes should count as outs; I can't stand batters taking 30 straight pitches in a row if they choose to do so. Plus the notion of All Stars having to participate in it is silly. Why can't guys like Russell Branyan, Adam Dunn, Mark Reynolds. etc. be in it every year? Guys like that who can just flat out mash should be selected. I'd much rather see someone like Branyan than Susuki.

24. DJ Young Says:

You say the Derby's inception came in 2000? Tisk tisk, it's been around since 1985

25. Andy Says:

Yeah apparently I got some bad info on Derby history and failed to check it. Weirdly I have no memory of the Derby from back then. It wasn't on TV back then was it?

26. Spartan Bill Says:

Andy

The original was a 30 minute show filmed in the off season at Wrigley Field in Los Angeles, Each show had 2 batters playing "innings". while one competitor hit, the other joined the commentator on the air.

Here is an 8 minute clip, you might find enlightening. Henry Aaron V Duke Snider. It appears to have been filmed after the 1959 season.

Winner got 2,000, loser took home a grand.

27. Andy Says:

I remember that show. I've actually seen quite a few episodes. Some network--I want to say Nickelodeon but that might be wrong--aired repeats of the show in the 1990s that I watched.

28. Fireworks Says:

Andy you are absolutely right in your conclusion that there is no real good or bad effect to be had by a player participating in the HR Derby, though obviously there can be exceptions. Like you said, the reason guys are asked to participate in the derby is because they have had excellent HR production in the first half, and for many of these guys, it's well above their normal production and likely to drop in the second half.

Personally I've never bought the "the HR Derby messes up guys swings" theory, and the best-cited example people pull out their butts--Abreu--was never a truly formidable HR hitter at any point during his career. He just had a pretty good first-half HR rate, got selected to the derby, went nuts, then had a little bit of a down year in HR production in the second half, which led to people saying "oh it messed up his swing." Nonsense.

29. Johnny Twisto Says:

I haven't read it but apparently Hardball Times tackled this question last year
http://www.hardballtimes.com/main/fantasy/article/do-hitters-decline-after-the-home-run-derby/

30. Rich Baxter Says:

Nice post, I am writing an article tonight as the All Star "Home Run Derby" 2010 is being played. The title is 'Does The Home Run Derby Need Fixing?' - the Derby is a long and drawn out affair, but a fan favorite.
I am going to credit and quote this article and link to it also. Ryan Howard, Albert Puljols, and David Wright, not in a Home Run Derby? Why?

Rich