Derek Jeter is a baseball master. What has made him so great through the years is his brain. You give Jeter a question about the game and he answers it in simple terms.
So why, going into the second home stand of the season, does it seem like Yankee Stadium is not the home run haven it was a year ago?
"I'm not that smart," Jeter said. "I'm not going to figure out wind patterns and tunnels. There are people who study that?"
Well, yes, there are. The ESPN Stats & Information team has dissected Yankee Stadium in its lab. Their hypothesis is the stadium is not the home run mecca it was cracked up to be.
In the Yankees' first six home games this season, there were just 13 homers, compared to 25 at the same point in 2009. The weather, the wind, the destruction of the old Yankee Stadium next door, and the lack of cheap homers have been poked and prodded by the ESPN Stats & Information professors to come up with their theories.
Meanwhile, Yankees manager Joe Girardi, without any knowledge of the study, has noticed there has been a change. Girardi doesn't pretend to know why.
"I know the first six games it didn't carry like it did last year," Girardi said. "That's the only difference I felt. It seemed last year, it turned around, around May 15th. It played like the old Yankee Stadium."
Not even ESPN Stats & Information, with all its charts and graphs and formulas, can say for sure. But here are some of their findings as to possibly why:
• There have been only two "Just Enough" home runs, compared to eight last year. A "Just Enough" homer, according to HitTracker, is a homer that clears the fence by 10 feet or less. There is often variance in this statistic from year to year, so this isn't that unusual.
• However, the average temperature has been seven degrees cooler (63 to 56) on average for Yankees home games this year. Lower temperatures usually mean less homers.
• The average wind speed is four mph faster this year (7.8 to 3.8). However -- and here is the big one -- the wind direction, according to ESPN Stats & Information, has changed slightly from a left-to-right field stream to a trajectory blowing in from left field.
• On April 17 and 18, 2009, the pitchers were Joba Chamberlain, Anthony Reyes, Zack Johnson, Jensen Lewis, Fausto Carmona, Chien-Ming Wang, Anthony Claggett, Edwar Ramirez and Jose Veras. There are not many groundball pitchers in that group, and some, if not most, are not very good. Over those two days, 14 of the last year's 25 homers were hit.
Everybody is wondering about the impact of taking down the old Stadium, and no one knows for sure what it is. "I have no idea," Girardi said. "You hear theories about the old ballpark. It changed during the course of the season last year."
Jeter, always one to simplify the game, doesn't plan to put on a lab coat anytime soon.
"You hit the ball, it will go out," Jeter said.
Andrew Marchand covers baseball for ESPNNewYork.com. Follow him on Twitter.