Does the Homerun Derby REALLY mess up players swings?

I love posts that dispel myths of all sorts. After reading about the psychology of our love with fanciful stories (narratives) fueled by information that fits our preconceived notions versus solid data driven evidence (especially concerning economics and science) versus solid data driven evidence (especially concerning economics and science), its not hard to see how our worldly observations are heavily biased. We hate feeling conflicted; we hate to be wrong.

The baseball Home Run Derby is no different.

The myth goes like this: Most players who participate in the Home Run Derby will have their swings irrevocably altered the rest of the season resulting in a huge drop in home runs. 


A great post on Fan Graphs examines the data and found some interesting results that helps dispel this myth:  FANGRAPHS POST

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The Home Run Derby is kind of counter-intuitive to many MLB managers. Old-schoolers like Mike Scioscia would rather his players did not participate, saying, “I haven’t seen somebody come away from that derby and be a better player for it.”¹ The Home Run Derby turns the team game into an individual competition. Players exhaust themselves and risk tweaking their swings, but has the derby really affected the second-half performance of its participants?

To answer this question I looked at what goes into a player’s stats. There is a lot of luck involved in baseball, so I took a look at the differences in the way players hit the ball before the derby compared to after the derby. Looking at the past five derbies, I calculated the average batted-ball flight for players that were healthy for both halves of the season

The HR to FB ratio drops considerably, and could explain a decrease in batting average and slugging percentage, as well as on-base percentage. It seems that players hit the ball the same way, just with slightly less power.

The large drop is ISO shows that indeed power does decrease for derby participants in the second half, and the overall line shows that players do perform worse. It’s not merely a function of hitting the ball to the wrong place, as the .oo6 drop in Bating Average of Balls in Play (BABIP) is not really significant. Players strike out a little bit more, but the notion that players change their swings and have trouble hitting the ball the same way after participating in the derby seems misguided when considering the small change in K% along with the consistent batted-ball percentages outlined in the first table.

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So, NO CHANGE IN TYPES OF BALLS HIT. I speculate that (all other factors being equal) given the small 1% increase in strikeouts, the drop in power (home runs) in the second half of the season could be the result of fatigue.

July 17th Drought Update

Drought conditions still exist in the west.

The corn belt is still enjoying good soil conditions.

HERE IS WHAT IT LOOKED LIKE IN JULY OF LAST YEAR

...NOW TODAY'S DROUGHT CONDITIONS

Does Rainfall Effect High Temperatures?

90 degree heat is here and its been a long time coming. After a rainy/cooler than normal spring along with the more recent 8-10 inch rainfalls over the last two weeks, this round of warmth is a welcome break. I don't want to lessen the significance of the flooding last week since many areas are still cleaning up. But the heavy rains and subsequent saturated ground is a welcome sign as the daytime highs soar north of 90.

FOX8 Front yard on July 13th -- Lush Green Grass!

I talked about this earlier in the spring and summer:  WET GROUND SUPPRESSES HIGH TEMPERATURES!  Large scale factors like the heat dome overhead can override this effect somewhat depending on how large in extent the wet ground goes.

Here is a map of the rainfall numbers compared to normal for the first 14 days of July.

Here is the location of this VERY STRONG AND DEEP heat dome. The center is right over Ohio. The 600dm (decameters--height of the high pressure dome) is a rarity over Ohio. In fact, last summer, I don't recall the heat domes over ANY part of the US pushing above 600.

When you superimpose the heat dome location over the rainfall map, you see that the center is over the saturated ground over Ohio and Kentucky. High temperatures on Monday only hit 91.

Last year, the heat dome was well west of Ohio yet daytime highs in July reached 98 TWICE. The ground in the first weeks of July was incredibly dry!

  

Historically, 42% of our 90 degree days occur in July.

 

We had many more days above 95 in the 1940s and 1950s than we've had since.

So will the wet ground override the effects of the strong OHIO CENTERED heat dome over the next few days keeping temperatures in the 90 to 93 degree range versus what happened last year at this time? 

I say YES.  Check back on Friday as the heat retreats west.