Tuesday, June 19, 2012

Adapting Expectations - Moving Forward

Over the past month, I've written a couple pieces on both how a lower run scoring environment has affected the production of hitters and pitchers. Clearly, we're living in a different world today compared to ten years (my reality is strongly tied to what's happening in baseball). But that doesn't make the recalibration of batting averages or ERA any easier. Without looking back at the league averages, it's tough to remember if an ERA at 3.50 is exceptional or average. Well, luckily for us, smart baseball nerds have solved this issue by developing stats that can weed out changes in run environment.

Hit the jump-

A quick look at a baseball-reference.com player page can help illustrate this point:

Mark Buehrle            ERA                                                                                     ERA+

I chose Mark Buehrle because he's scary consistent and helps makes this point a little simpler. Also, I hope that graphic makes some sense, I'm no computer wizard. The two columns I'd like to point out are ERA and ERA+.

ERA you all know about, so I'm not spending any time on that. However, ERA+ may be new to some of you or you only have heard about it passing. But here's the gist- it measures a pitchers success, based on ERA, against the major league average. For example, a completely league average ERA is 100, and an ERA that is 80% of the league average (i.e. good) is 125. Anything around 150 is spectacular and an ERA+ of 200 is where elite relievers like Mariano Rivera hang out.

So, back to Buehrle. Over the past six years he's posted ERA+'s of 121 and 122, 4 times. This is insanely consistent. But a look at the ERA does not tell the same story, where he's posted 3.79, 3.84, 3.59 and 3.41 those same seasons.

Out of context, one could infer he was improving. Although, in reality he has stayed the same, his environment has changed.

The batting equivalent to ERA+ is OPS+. Again, 100 is average, over that is good, below that is bad. As an example, Ryan Doumit has a 101 OPS+ this season.

These '+' stats are a good way to get a little context, but due to the inherent flaws of ERA and OPS, they aren't ideal. (ERA is affected by many factors out of the pitchers control, like fielding and luck. For more info there good 'Voros McCracken DiPS theory" ; and OPS over-emphasizes slugging percentage in relation to on-base percentage)

For an even more in-depth statistical measure of value you will have to check out wOBA, FIP and WAR. Which all probably sound a lot more daunting than they actually are. But as for today, I'm not getting into that fun stuff.

Once again, beware of the environment. Compare a player to his colleagues and not past performances and baselines. If you can do that, you're golden.

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