Posted by Neil Paine on September 9, 2009
Among the wealth of information we have here at Baseball-Reference, some of the coolest can be found at our splits pages -- in fact, there's so much data to be had that I get the feeling many users don't even know the extent of what they can find. So over the next week or so, I'm going to be taking you through a guided tour of the splits pages to show you exactly how many awesome factoids there are to be uncovered there.
First, pick a player, any player... How about Hank Aaron? Here are his career batting splits. At the top of the page are the usual raw splits, like platoon (vs. RHP/LHP), home/away, half-by-half or monthly, etc. For career stats like these, though, sometimes it can be hard to put things in an understandable context. That's why we have the option to "View splits adjusted to be per 162 games or 650 PAs" at the top of the splits section -- this function recalculates each batting line to place them in the easy-to-understand format of a full season, prorating the splits to 162 games when based on full-game data and 650 PAs when not. Now you can see that versus righties, Hammerin' Hank had the equivalent of a 34-homer season on average every year, and became a 39-HR-a-season guy when facing lefties. And if he could play all season like he did in March and April, he would knock 44 balls out of the park on average every year. This is useful because it gives the splits "the power of language" -- because we intuitively know how impressive 44 HR was in Aaron's day (it was only done 39 times in Hank's 23-year career, including 6 by Aaron himself), it can have more meaning at a quick glance than something like 93 total home runs in 339 games.
But switch back to unadjusted mode, because there's more to see. Under each split, the description of the split type is in red text, which means it's a tooltip that can be clicked for more in-depth data. For instance, clicking on "vs LHP as RH" at Aaron's career splits calls up his year-by-year results in that particular split -- in the pop-up box, you can see the progression of Hank's career versus left-handed pitchers. And if you want to share this table with someone else, there's a "permanent link" function in the top right-hand corner of the box that will allow any user to visit the same split you were looking at. In fact, while we're on the topic of linking, close the box and note that next to the header for every split is a "direct link" button that will send people to any specific split within the player's page (for example, Aaron's performance by team outcome). This is just another way by which you can share an interesting tidbit or settle an argument quickly.
Now take some time to scroll down the page and note just how many statistical breakdowns are offered on the splits page... If there's a situation that you're looking for, I would almost guarantee that our splits have it (and if not, there's always the Play Index's Event Finder). And for more modern players than Mr. Aaron, we offer even more categories on the splits page -- take, for instance, Joe Mauer in 2009. On his single-season page you can find many of the same splits, but also breakdowns of his numbers over the last 2 weeks, the last month, or the last calendar year. You can also check out some batted ball splits, like performance by hit location and hit trajectory. Note as well that this data extends back to 1988, so if you wanted to know that Rickey Henderson hit .286 on ground balls in 1990, you can find that stat, too.
We also offer special OPS splits called "tOPS+" and "sOPS+"... tOPS+ compares the players OPS in a specific situation to his total OPS for the entire season, so you can see that Chipper Jones is only 91% as effective from the left side of the plate as he has been overall this year. On the other hand, sOPS+, or "split OPS+", compares a player not to his overall performance, but to the rest of the league at that particular split. So you also see that even though Chipper is less effective as a lefty batter than he is from the right side, his OPS is still 7% better than how the rest of the league's lefty batters did vs. right-handed pitching.
Anyway, go ahead and play around with the splits, because I know that you'll be able to find some really cool nuggets of information if you dig deep enough. Like that only 4 of Barry Bonds' record 73 home runs in 2001 were to the opposite field. I mean, who would know things like that if it weren't for our splits?