Stat SPaz Week, Day 4: HR/FB

The Starting Line
by Evan "the Censor" Dickens
evan@fantasybaseballsearch.com

After our initial jaunt through some of my favorite skill-based statistics, it's now time to turn the tables and look at statistics that identify some of the luckier (and unluckier) pitchers in baseball--which is the real information that you want when targeting buy and sell options as trade season hits the critical point over the next week.

The theory behind HR/FB is this--for the most part, with sensible adjustments for homer-friendly ballparks, you can reasonably expect that across the major leagues, fly balls are relatively interchangeable and will tend to leave the park at the same rate. In other words, if a pitcher is going to give up a fly ball, it's not because of any particular skill that more of his fly balls stay in the park than leave. The major league average is right about 10%--for any given pitcher, you can reasonably expect one out of every ten fly balls to land in the stands. Significantly higher or lower percentages indicate some potential regression--and that regression is that much more important for pitchers with higher FB%.

By the way, it's very important to note that this is a luck statistic only for pitchers. Clearly, it's a different story for batters, but pitchers are assumed to face an even distribution of batters over the course of a season.

First, some historical perspective on HR/FB:

2004
Best: 5.6% - Tim Hudson, OAK
Worst: 18.2% - Greg Maddux, CHC

2005
Best: 4.9% - Dontrelle Willis, FLA
Worst: 18.9% - Derek Lowe, LAD

2006
Best: 5.7% - John Lackey, LAA
Worst: 16.9% - Cory Lidle, NYY

2007
Best: 4.1% - Chris Young, SD
Worst: 17.7% - A.J. Burnett, TOR

2008
Best: 5.1% - Cliff Lee, CLE
Worst: 16.1% - Brandon Backe, HOU

Pretty evident that those with unsustainably low HR/FB percentages had them in years that we can look back on and say "Boy, they had a great year that year...what happened afterwards?" Lackey is a notable exception, and Lee looks almost as good...for now. But you'll notice by looking at any given pitcher's five-year history that if they play in a relatively neutral park, HR/FB is subject to wild fluctuations. In my world, we call that Luck!

Now, let's look at the top and bottom five so far this year.

Five Best 2009 HR/FB through 7/22/2009:
1. 2.9% - Zack Greinke, KC
2. 3.3% - Joel Pineiro, STL
3. 4.7% - Clayton Kershaw, LAD
4. 4.8% - Dallas Braden, OAK
5. 4.9% - Tim Wakefield, BOS

Seem like a few pitchers on that list are having unexpectedly good years? Here's part of the reason. Greinke's total absense of HR is downright scary and there's no possible way it can continue for him. He's not exactly a major GB pitcher, either; a 38% FB rate bears out to a guaranteed ERA increase on the horizon. Not saying he's a fraud--he's just not this good! Don't worry too much about Pineiro who has the best GB rate in the majors, but Wakefield is on the other end of the spectrum--his 45% FB rate is a massive danger sign and he has never posted a HR/FB lower than 9% before. When he comes back, brace yourself for the regression (that, seriously, you always knew was coming).

Five Worst 2009 HR/FB through 7/22/2009:
1. 18.0% - Josh Geer, SD
2. 16.8% - Chris Volstad, FLA
3. 16.5% - Braden Looper, MIL
4. 15.9% - Ricky Romero, TOR
5. 15.4% - Trevor Cahill, OAK

Five relatively unappealing pitchers? Partially because their unlucky HR rate has showed you the worst they have to offer. Volstad and Cahill in particular have high enough FB rates, and enough talent, that you might be able to make the case that there is speculative skill underneath their mediocre numbers. Don't go running to pick these guys up--but don't let their 2009 difficulties define them in the future.

Tomorrow, the Censor's favorite acronym to pronounce as a single word! See you then.

~Evan the Censor