The smallest difference all time is by Pop Snyder, whose .254 OBP was just 19 points higher than his .235 BA.He walke 83 times in his career, or once every 45 PAs.

]]>How the hell have you heard of IsoP but not IsoD (Isolated Discipline, which is what this is)???

]]>JohnnyTwisto: I'd say Walk Rate is a pretty good name for it. The problem is that their denominators are different (AB for BA, PA – SH for OBP), which means you're not really measuring the rate of anything. With Isolated Power, you're measuring the rate of *extra* bases earned per at-bat since both BA and SLG use AB as their denominators, but with WR you're over-deducting for hits.

To clarify, consider the following simple example: A player gets 100 hits and 100 walks (no HBP or sacs) in 400 AB.

OBP = 200 / 500 = .400

BA = 100 / 400 = .250

When you subtract the two, you get

WR = .400 - .250 = .150

Since the denominator of OBP is PA (actually PA – SH, but with no sacs we’ll simplify), the .250 we’re subtracting would represent .250 * 500 PA = 125 times on base. But that came from only 100 hits, so essentially we’re taking away credit for 25 of the player’s walks because he got 100 hits. If that same player had only gotten 50 hits and 100 walks in those same 400 AB:

OBP = 150 / 500 = .300

BA = 50 / 400 = .125

WR = .300 - .125 = .175

So his WR goes *up* .025 because he’s a lousy hitter otherwise. In this case, the .125 we’re subtracting would represent .125 * 500 PA = 62.5 times on base. Since that came from only 50 hits, we’re essentially taking away credit for only 12.5 of the player’s walks instead of 25.

The fact that sacrifice flies are also counted in the denominator of OBP but not BA makes it possible for someone with few or no walks and HBP but a significant number of SFs to have an OBP lower than his BA, and thus a negative WR.

While "WR" is easily computed because BA and OBP are often already calculated, a more reliable way to measure it is simply,

(H+BB+HBP) / PA

or you could use PA – SH (the same as OBP) in the denominator if you prefer. This would calculate the true walk rate, which is what I think we were getting at in the first place.

]]>OBP - AVG

=(AB(H+BB+HBP) - H(AB+BB+HBP+SF))/(AB(AB+BB+HBP+SF))

=((BB+HBP)(AB-H) - H(SF))/(AB(AB+BB+HBP+SF))

=(1-AVG)(BB%+HBP%) - AVG*SF%

(where in these rate percentages, SH's are removed from plate appearances)

So, if my math is right, having a great walk rate and hit-by-pitch rate is much of the story, but having a low batting average helps.

]]>We need a good name for this. Isolated Power, of course, is SLG - BA. "Isolated On-Base" doesn't sound that good. "Isolated Walk Rate" isn't quite correct.

]]>To get back on-topic...Yank Robinson had a .134 delta - over a 10-year career. Check out his 1890 season, .434 - .229 = .205. See also Jack Crooks, .145 over an 8-year career.

]]>