Another reader requested piece today: testing the myth (or is it) of homerun derby participants changing their approach and suffering second half regresses.
Taking the combatants from 1998 through 2007 (84 total) I looked up their first half and second half OPS (with help from user SaberToothedPie) to see if the players really did suffer a let down post derby. Why not homeruns? Because for one the games are disproportioned and 15 homers in the second half is actually more impressive than 15 in the first half on a rate scale. Hitters also can have their ratios like HR/FB% regress or progress, meaning homeruns just even out over the 162 game season. Instead we're looking at an outline of their entire offensive performance, or at least a summed up version.
Above you see the 843 players, their first and second half OPS, a "net" column (second half OPS - first half OPS) and a "W" column - only the players who won that derby have a W listed. 50 of the 84 players either saw no post-derby gain or suffered an OPS drop, meaning only 34 had positive post-derby experiences.It's important to note that Ivan Rodriguez played in all of 10 games following the derby, hence his absence.
So can we predict a fall off for some of the contestants in tomorrow's derby? It seems quite likely that at least a few will have lower second half OPSes, but correlation doesn't always stem from causation, so while people may think the derby affected a player, there's nothing too conclusive to be drawn, despite only a .443 R2 between first half and second half OPSes which I actually figured would be a bit higher.
To see if this is regular or not we took the top 50 homerun hitters from 2007 and compared their first and second half OPSes - since in the end we are talking about some of their power hitting brethren who, again in theory, didn't "mess up their swings" or anything of the sort. The R2 of the first and second half OPSes: .344.
That means your average HRD participant actually has a better chance at maintaining his first half OPS than your top 50 homerun hitters, at least in 2007.