Chewing on SIERA

Much good work has been done in recent years to quantify the value of baseball players. There has been a lot of discussion just in this space concerning the new stats and what they mean to the game and to the average fan. One major benefit touted by these new statistics is the ability to project a player's performance based on detailed analysis. Baseball Prospectus has developed a strong following for doing just that. Their PECOTA projections are the most respected in the game. As such, the Fan spends a lot of time looking at their data. One article (the site is a subscription site so you can't read it if you aren't a member) based on their projections talks about pitchers who should do better than expected this coming year or worse than expected based on their projections. Their criteria is a new stat they have created called SIERA, which tries to only measure ERA based on issues the pitcher can control. It's very interesting, but one thing seems to nag at the Fan.

The writer uses Randy Wells of the Cubs as an example of a pitcher who should not be as successful this year as he was last year. Here is what the writer says:

Wells and Happ found themselves intertwined for much of the 2009 seasons as NL Rookie of the Year candidates and also in that the controllable numbers indicated both would regress in 2010. Wells barely touches 90 mph with his fastball and he doesn’t miss many bats, but he is
stingy with walks and keeps the ball on the ground. All of that is well and good, but what one would expect from a third or fourth starter, which is what his SIERA indicates.

Again, there is a nagging feeling that the numbers don't tells us everything here. How do you measure a pitcher that is just darn good at getting a batter to hit the ball where the pitcher wants him to hit the ball? Can you measure such a thing?

Some of the big things SIERA looks at is strikeouts per nine innings, walks per innings, strikeouts to walk ratios and home runs allowed. So the argument against Randy Wells continuing to have the kind of success he had last year is that he didn't strike out that many batters and he was "lucky" with a low BABIP. In other words, most of the balls the hitters put in play were turned into outs. BABIP is a favorite stat here in the FanDome. But again, something nags at the Fan when he uses it. The general consensus is that the BABIP (batting average on balls in play) should be around .300. Get over that and the pitcher is unlucky. Get under that and the pitcher is lucky. Mostly it makes sense. But not completely.

Take for example a guy like Jim Kaat. Kaat won 283 games in his career despite striking out only 4.9 batters per nine innings. And Kaat's career BABIP was .283. So was his 283 wins and great success a matter of 25 years of good luck? The Fan guesses that's possible. But perhaps Kaat was really, really good at getting batters to hit the ball where he wanted them to hit it.

The Fan has watched Mariano Rivera pitch for fourteen years now. Yes, the man does strike out guys, but not as much as some closers. Yes, he is stingy with walks. So he is everything a SIERA stat would ask for. But one thing about Rivera that the Fan has consistently noted is his ability to get guys to ground out weakly to the pitcher, the second baseman and the first baseman. So his career BABIP is .266. Is he just lucky when they hit the ball? No, the Fan contends that he is awesome at getting the batter to hit the ball the way Rivera wants them to hit the ball.

Greg Maddux had a career BABIP of .286. Lucky? Hardly. He too was unbelievable in controlling where the batter hit the ball. Luis Tiant won over 200 games. His career BABIP was an amazing .264. Lucky? At this point, the Fan will let you decide. Want more? Okay, here are a few more examples of low strikeout, successful pitchers and their career BABIPs:

Mel Stottlemyer - .264
Jake Peavy - .287
Chien-Ming Wang - .295
Tommy John - .285

Some pitchers won't blow you away with stuff. Some will not blow you away with K/9 or K/BB ratios. But they were just really good at locating their pitches in a way where the batter hit the ball with predictable results. So SIERA and many of the new stats are good things. The Fan likes them. But they don't account for baseball smarts and the ability to duplicate strategy over a long period of time to force batters into hitting the ball in such a way that damage would be negligible.

SIERA may or may not be right about Randy Wells. Time will tell. But in 2009, it simply looked like Randy Wells was just great at getting batters to hit the ball where he wanted them to hit it.