The bloggers at Pinstripe Alley, a Yankee fan blog, looked at the first and second half OPS of all HRD participants since 2000 (except IRod in 2000 because he barely played in the second half). Their conclusion was that the OPS dropped .042 points, which they described as "not huge".
I wanted to slice the numbers a little differently, using essentially the same data set that Pinstripe Alley used.
I wondered whether HRD participants with significant all-star game or HRD experience were affected differently than inexperienced players. I categorized experienced players as those who, at the time of the HRD appearance in question, had made the all-star team at least twice before or had participated in an official HRD before. Of the 79 players in the data set, 40 were experienced using that filter, and 39 were not. That worked out pretty nicely. :)
I used 5 stats:
Strikeout percentage (SO/AB):
Experienced players had their K% increase from 19.2% to 19.9% in the second half, for a 0.7% increase. A difference not worth commenting on further.
Inexperienced players had their K% increase from 20.3% to 21.8% in the second half, for a 1.5% increase. It's not a huge difference from first half to second half, but the difference is twice as large as for experienced players.
OPS (OBP+SLG):
Experienced players had their OPS decrease from 1.011 to .987 in the second half, for a .024 decrease. That's not a big difference.
Inexperienced players had their OPS decrease from .956 to .913 in the second half, for a .043% decrease. Again, not a huge difference from first half to second half, but the difference is almost twice as large as for experienced players.
I also wondered how much OPS was affected by high first half BABIPs and regression to the mean in the second half. As an average, neither group had a significant BABIP change from first half to second half.
Nine (9) of the experienced players had their OPS drop 100 points or more, and five (5) of those had their BABIPs drop 25 points or more. By contrast, fifteen (15) of the inexperienced players had their OPS drop 100 points or more, and nine (9) had their BABIPs drop 25 points or more. So inexperienced players were hit more dramatically, but essentially the same percentage had significant BABIP adjustments as a contributor.
Five (5) of the experienced players had their OPS rise 100 points or more, and three (3) of those had their BABIPs rise 25 points or more (and the other two had rises of 14 and 19 points). Only three (3) of the inexperienced players had their OPS rise 100 points or more, and all of them had a rise in BABIP of 25 points or more.
BABIP seems to be a partial explanation for significant drops in OPS in the second half, but seems to be a more significant factor to significant OPS gains in the second half.
ISO (SLG-AVG):
Experienced players had their ISO decrease from .293 to .279 in the second half, for a 14 point decrease. No big deal.
Inexperienced players had their ISO decrease from .277 to .243 in the second half, for a 34 point decrease. More significant, but again, the difference is two and a half times as large as it is for experienced players.
BABIP:
Neither group experienced a significant change in BABIP. The inexperienced players actually got a little 5 point BABIP bump in the second half. Both groups started with substantially equivalent BABIPs. See note above under OPS.
HR/Contact Percentage (HR/(AB-SO)...essentially, how many balls contacted flew out of the park):
Experienced players had their HR/Contact% decrease from 9.3% to 9.0% in the second half, for a .3% decrease. No significance at all.
Inexperienced players had their
HR/Contact% decrease from 8.7% to 7.2% in the second half, for a 1.5% point decrease. That strikes me as more notable, but again the most glaring difference is that the change is five times bigger than for experienced players.
Conclusion
One could conclude from the numbers above that the effect on second half performance is not tremendously significant for any HRD participant, and is basically non-existent for the players I've named as "experienced."
On the other hand, the difference between "experience" and "inexperience" is probably just regression at work. Consider that everyone in the experienced data set was appearing in at least their third all-star game, with one exception of a player who participated in HRD twice before ever making his third all-star appearance. So for the most part, these guys are true all-stars and less likely to be in the game because of a statistical fluke.
The so-called inexperienced players have more trouble in the second half because their first half performances were surprises. Brandon Inge in 2009's HRD was the best example. He went from having the best first half of his life, to being literally one of the worst hitters in MLB during the second half (how do you like a OPS of 541?).
It's not that all-star game or HRD experience makes a player seasoned enough to not let his swing get screwed up by HRD. It just means those are the really good players -- the perennial all-stars -- who naturally have more consistency. After all, the first half numbers of experienced players are better than the inexperienced players across the board...lower K%, a full 60 points better on OPS, 16 points better on ISO and a higher HR/Contact %.
I have a quick part 2 to post, because I also sliced the data by the number of swings the player took in the HRD. To come...
