In many saber-metric circles BABIP (BA for balls in play) is used. Would the rest of the “slash line” (OPS and SLG) for balls in play be useful stats?
OBP (I assume you mean) on balls in play would be nearly useless because it would exclude walks and HBPs. It would count sac flies against the batter though.
… and a little googling reveals that BABIP already includes sac flies in the calculation, so I guess OBPBIP would be identical to BABIP.
Cool. Would SLIP be useful?
It seems to me SLG-BIP wouldn’t tell you anything SLG minus batting average doesn’t. Slugging is, by definition, a measurement of power. Doubles, triples and home runs are generally not a function of luck, as BABIP sort of is - I mean, they can be, but not as much as singles, and the bigger the hit the less luck is involved. You can get a double out of luck (bad outfielder, for instance) but it’s hard to hit a lucky home run.
So really the stat already exists that you need - Isolated Power, which is just SLG-BA. Slotting it in to balls in play strikes me as serving no obvious purpose.
Slugging on balls in play does tell you something isolated power doesn’t; it’s just not something about the batter. Slugging on balls in play is a defensive statistic. Think about it - the pitcher’s job is to keep the ball out of play. The hitter’s job is to put it into play. The defense’s job is, if the ball is hit into play, to make outs and keep runners from advancing.
If we’re limiting ourselves to balls in play, we know the hitter’s done his job to some extent or another. Slugging tells us, when the batter puts it in play, how far he gets on the bases, on average. For an individual hitter, the stat is going to tell us how well his, uh, balls have been defended. If we look at a team’s defensive SLGIP over a large enough sample, what we should learn is how efficient they are at taking hits and limiting the damage. Specifically, if you really want to dig into it, I think what you’ll find is that it’s a measure of outfield defense in particular, since the infielders generally have more influence over hits vs. outs than over triples vs. doubles vs. singles.
So SLGIP, in my opinion, tells you how good the outfielders have been at tracking the ball down and getting it into the infield.
on edit: for the same reasons, I suppose it could also be a measure of baserunning in extreme cases.
Thanx Rick! It seems Iso Power is the same thing.