Case study: Dan Haren
Dan Haren had a great 2007, one in which he won 15 games and dominated the league with a 3.07 ERA. He’s put up three straight seasons of making all his starts for Oakland, he’s moving to the weaker NL and he’s turning 27 this season, making him a prime breakout candidate, right? He finished with six dominant starts out of 34, ranking with the likes of Chris Young, James Shields and Matt Cain. That’s good company. Some stats guys are calling for him to lower his ERA by half a run in 2008. Half a run. Can we really expect that kind of improvement out of Haren?
First off, don’t forget that Haren played for the Oakland A’s. McAfee Coliseum is infamous for its vast expanses and generous foul territory, making it a pitcher’s dream come true. Haren had an ERA of 2.82 at home, and 3.34 on the road. Indeed, Baseball Prospectus gives his peripheral ERA as 3.66 last season. And now he’s moving to Chase Field in Arizona, which had a park factor of 1.111 in 2007. In other words, he’s moving from the second-best pitcher’s park to the fifth-best hitter’s park in the Major Leagues. So even if he reproduces last year’s success, we’re looking at an expected peripheral ERA of around 3.60, and his home starts could give him an ERA of 4.00 if that park factor holds up. Split the difference, and Haren’s looking at a final ERA of maybe 3.80 for the year. Correct a little for the NL shift, and it’s maybe 3.60-3.70. PECOTA’s weighted mean average has him at 13-9 with a 3.84 ERA, for comparison.
Another consideration is Haren’s second half stats. Haren was the proud owner of a 2.30 ERA at the ASB, but his second half was not nearly so pretty: 5-6 with a 4.15 ERA. That’s statistical regression if I’ve ever seen it. Considering his lifetime ERA is 3.82, I’d wager that his second half is more reflective of his abilities than his first half was.
Lastly, Haren’s workload has been heavy in Oakland. He threw 3,642 pitches last season, and that raises his risk of missing some time. There’s always some significant risk with pitchers.
Don’t get me wrong, I still think Haren’s a good pitcher, and I have him ranked 9th among starters this year. Paired with Brandon Webb, the Dbacks have a very strong rotation going into 2008. Just have realistic expectations is all I’m saying. Once again, I have to say that Billy Beane has sold high on a guy and made out like a bandit.
