Monday, January 11, 2010

Wrigley Field: Park Factor


In the summer of '98, I attended a Cubs game with some friends and watched Sammy hit two balls deep to center field. As the ball went up in the air, you could see it drift into the stands but then the wind came keeping the ball in-play. It is my assumption that if the wind was blowing out that day, these balls would have been home runs. Who knows, maybe Sammy would have finished with 68 HRs...70...72...or better yet, he would know what questions are being asked of him in a congressional hearing (ok, that was low I know, but this is a blog).

So I started to think about Wrigley Field's dimensions and wind patterns and how they affect the game and how the Cubs win/loss record could be affected by whether the wind is blowing in/out that day. It is true that wind patterns do affect Wrigley...so much so that ordinary fly balls can turn into home runs (hence, home run to fly ball ratio...which I will have to research in a later post).

The following is an attempt to explain the basics of Park Factor for Wrigley Field. Throughout this process, I have found that their needs to be additional research conducted such as: how often the wind blows in/out, home run to fly ball ratio, and total foul balls hit. All of which I will bring to you in the upcoming months (just send a little reminder).

But for now, enjoy the basics of park factor. I present to you, the wonderful Wrigley Field...and it's affects on our Cubs.

A couple more things worth mentioning before we dive in:
1.)From home plate to the (left field) foul pole is 355', the (right field) foul pole is 353'.
2.)The wall is approximately 11.5'
3.)Here is a link about the unusual wind patterns (from Wikipedia).
4.)Taking a look here, we see there is not a lot of overall foul territory at the Friendly Confines.


To consider park factor, I will use the following equation:

Park Factor = (Runs Scored[home]+Runs Allowed[Home]/Number of Home Games)/(Runs Scored[road]+Runs Allowed[road]/Number of road Games)

A rate higher than 1.000 favors the hitter. Below 1.000 favors the pitcher.

Wrigley Field - Overall Runs
Year
Park Factor
Rk
Run Production (+/- %)
Favors
2001
.930
25
Decreased run production by 7%
Pitchers
2002
.953
20
Decreased run production by 4.7%
Pitchers
2003
1.061
11
Increased run production by 6%
Hitters
2004
1.123
5
Increased run production by 12%
Hitters
2005
1.013
15
Increased run production by 1%
Hitters
2006
1.075
6
Increased run production by 7%
Hitters
2007
1.172
2
Increased run production by 17%
Hitters
2008
1.068
8
Increased run production by 6%
Hitters
2009
1.146
3
Increased run production by 14%
Hitters
Avg
1.06
10
Increased run production by 6%
Hitters

So what do we see here? We see that over the past 9 years, Wrigley Field has become more of a hitters park with an average ranking of 10th in the league for increased run production. Honestly, I was expecting Wrigley to rank somewhere in the middle overall. I must admit that I am a little surprised by this.

Ok so that was overall runs. What about if we measured home runs only? Where would Wrigley Field rank then?

Wrigley Field - Home Runs
Year
Park Factor
Rk
Home Runs (+/- %)
Favors
2001
.904
24
Decreased home runs by 9.6%
Pitchers
2002
1.252
9
Increased home runs by 25%
Hitters
2003
.975
18
Decreased home runs by 25%
Pitchers
2004
1.329
2
Increased home runs by 33%
Hitters
2005
1.054
12
Increased home runs by 5%
Hitters
2006
1.212
5
Increased home runs by 21%
Hitters
2007
1.150
8
Increased home runs by 15%
Hitters
2008
1.163
7
Increased home runs by 16%
Hitters
2009
1.006
15
Broke even (0%)
-
Avg
1.06
10
Increased run production by 6%
Hitters

Again, we see Wrigley favor the hitter from 2001-2009. Maybe this is why Jim Hendry has focused his efforts on acquiring power guys (Soriano, Ramirez, Lee) throughout his tenure.

Coming (sometime in 2010)... Wrigley Field, HR/FB ratio (2001-2009)!!! Which has been very difficult to track down. BUT I promise all you Cubs Stats readers out there, if I have to camp out at Clark and Addison to bring you this story, I will.

5 comments:

  1. Great post, Will! I must say, 10th overall does seem oddly high. Wrigley's standard deviation, however, is probably the highest, bar none. So many times it seems to be feast or famine -- either blowing in 16 MPH, or out 23 MPH.

    I wonder if we can examine the effect of the foul territory? Maybe (Foul Outs)/(Wrigley Games) vs. (Foul Outs Elsewhere)/(All other Stadiums' Games)? I dunno. If we can find that kind of data, it would be super fun to look at.

    ReplyDelete
  2. EXACTLY! I think Wrigley has got to have one of the highest if not THE highest foul ball numbers in the majors (at least that's my fuzzy assumption). I definitely want to find that data as well as hr/fb ratio.

    ReplyDelete
  3. Another thing I just noticed, something happened after 2002 or maybe it's sheer coincidence but the Cubs haven't been below 1.000 since then. We know the wall didn't move...it'd be interesting to see the wind patterns going back to then as well as if the park had any modifications (e.g.-more infield seats) but I do not think that is the case.

    ReplyDelete
  4. I'm inclined to think it's random variation, but I have no statistical reason to think so.

    ReplyDelete
  5. i think i would be fun to know the ratio of day when the wind is blowing in compared to days when the wind is blowing out

    ReplyDelete