Here's a Thought: Debunking the Myth of Cole Hamels' Regression

Nathaniel StoltzSenior Analyst IDecember 21, 2009

PHILADELPHIA - OCTOBER 08:  Starting pitcher Cole Hamels #35 of the Philadelphia Phillies throws a pitch against the Colorado Rockies in Game Two of the NLDS during the 2009 MLB Playoffs at Citizens Bank Park on October 8, 2009 in Philadelphia, Pennsylvania.  The Rockies won 5-4.  (Photo by Jeff Zelevansky/Getty Images)
Jeff Zelevansky/Getty Images

Cole Hamels went 14-10 with a 3.09 ERA in 2008. He ended the year a World Series hero.

Cole Hamels went 10-11 with a 4.32 ERA in 2009. He ended the year a World Series bust.

Naturally, any fan seeing this would think that Hamels had some sort of huge fall from grace; he must have done more wrong in 2009 than 2008.

The media was all over this line of thinking, particularly in the playoffs (when, admittedly, he did struggle, unlike his excellent 2008 postseason).

Not so fast.

I was entering data into my True ERA spreadsheet today, and I was entering Hamels' tRA in from Fangraphs when I noticed something.

Hamels' Fielding Independent Pitching numbers from 2008 and 2009 are exactly equal, at 3.72.


Then again, in an article last night, I showed that Astros lefty Tim Byrdak was wildly underrated by FIP, so just because FIP says Hamels was the same pitcher in 2009 doesn't mean he was.

But everywhere I looked, the numbers said the same thing.

Hamels' xFIPs from 2008 (3.63) and 2009 (3.69) are very similar, as are his 2008 (4.18) and 2009 (4.29) tRAs. My own new metric, True ERA, has Hamels at 4.15 for 2008 and 4.20 for 2009.

So what in hell is going on here?

Hamels' strikeout rate inched upwards this year, from 7.76 K/9 to 7.81. His walk rate decreased slightly as well, from 2.10 BB/9 to 2.00.

This led to an improved K/BB ratio of 3.91, up from 3.70 in 2008. His homer rate (1.11 HR/9 in 2008; 1.12 in 2009) was virtually unchanged as well.

Indeed, the ERA difference can be explained in the most obvious placesBABIP and strand rate. In 2008, Hamels' BABIP was .270 and he stranded 76.0 percent of runners. In 2009, those figures were .325 and 72.1 percent.

In particular, the BABIP difference is the cause of Hamels' problems. The only way this could be his fault is if he allowed harder contact in 2009 than 2008.

He didn't.

In fact, Hamels' line drive ratethe best indicator of how "hard" a pitcher gets hit, improved from 21.8 percent to 20.8 percent. 

Given his 20.8 percent line drive rate in 2009, the .325 BABIP likely isn't a fluke, but given his 21.8 percent mark in 2008, the .270 mark in 2008 is wildly out of line. It should be around .330 to .340.

But Hamels, benefiting from the defense of Chase Utley, Jimmy Rollins, Shane Victorino, Pedro Feliz, and Jayson Werth, happened to have his fielders catch almost 20 percent of these balls that should've gone for hits. Hence, a .270 BABIP and a Philadelphia hero.

The numbers suggest that Hamels himself was about a 4.00 ERA pitcher all along. There wasn't anything wrong with the lefty in '09; he had just gotten lucky in 2008, and expectations were set higher than they should have been.

So what does this mean for Hamels going forward?

Well, we know three things about him.

The first two are good: for one, he can shut down an opponent any given day, and second, his K/BB ratio is excellent.

The one negative thing is that contact against him tends to be hard, as evidenced by the high liner and home run rates (Philadelphia's park and Hamels' flyball ways don't help the latter number).

An excellent defense was able to counteract this in 2008, masking the problem, but it is a very real problem.

Hamels may need to throw a few more chase pitches out of the zone to keep the ball out of the middle of the plate. That may hurt his walk rate a little bit, but it would likely help his strikeout rate while reducing hard contact.

He pitches in the zone around 53 percent of the time, well above the 49 percent MLB average. He may work best at 50-51 percent.


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