Comments on: Temperature Does Not Explain the Decline in April Home Runs

By: JC

JC — Sat, 31 May 2008 17:59:47 +0000

HR/G are for all games. When I only include outdoor games HR/G looks similar. I didn’t report this because the question of interest involves all home runs and it would just be repetitive.

By: Patrick O

Patrick O — Sat, 31 May 2008 17:11:48 +0000

You say you exclude temperature data from indoor stadiums, do you also exclude the HR/G from those games?

By: Marc Schneider

Marc Schneider — Fri, 30 May 2008 14:06:32 +0000

I know that MLB has pooh-poohed this in the past, but has anyone considered that perhaps the balls are different? I know someone always brings this up when home runs go up or down but I have seen some balls hit at the new Nationals Park that seemed to be really crushed and didn’t go out. Even if one were to accept that steroid testing is a partial explanation, I doubt that these players lost all of their strength overnight. (Not to mention the fact that home runs are more a matter of technique than pure strength anyway.)

By: Sal Paradise

Sal Paradise — Fri, 30 May 2008 02:11:46 +0000

If you don’t want suggestions, then could you please post the data for game-time temperatures?

Specifically, I think it would be more accurate to calculate FB/HR modified by park factor rather than HR/G for the simple reason that if the sample is skewed (more groundball pitchers in warm/cold parks for instance).

After all, if you have warm stadiums getting 70% of the fly balls even if the average temperature is lower over the entire country, the data isn’t going to necessarily reflect what actually happened.

By: Matt C.

Matt C. — Thu, 29 May 2008 19:25:07 +0000

Oh and what about Humidity? Temperature may be higher and/or lower but from what I understand from the little physics I know if the air is more humid a ball will travel farther. If this is incorrect, please feel free to correct me.

By: Matt C.

Matt C. — Thu, 29 May 2008 19:20:45 +0000

My only question would be, okay if it’s not temp or steriods, could it be that pitching has just gotten better? Would there be any way to adjust for the quality of the pitching? Obviously if pitching is good homers will decrease, but how much impact does that actually have on the number of homeruns? From a novice position I wouldn’t even know how to control for pitching quality.

By: uncle ran

uncle ran — Thu, 29 May 2008 18:42:06 +0000

its just like the ballistics of a bullet air temp, humidity, and altitude all affect the bullet’s performances.

By: JC

JC — Thu, 29 May 2008 17:20:40 +0000

I may look into some older data soon.

JD,

I suspect air pressure and humidity matter, but I don’t have data on these things.

By: JDMaker1

JDMaker1 — Thu, 29 May 2008 17:15:08 +0000

JC, very interesting data. Do you think here is any interplay between air pressure/humidity and number of homeruns?

By: J

Thu, 29 May 2008 15:29:52 +0000

Another great post! I can’t wait for the follow up.

I’d be interested to see how this looks historically, rather than just the last 8 years or so. What about those red hot 90s days?

What about new parks opening up? There’s much to be discovered.