Homer Bailey’s shiny new six year, $105 million extension is a clear sign that the Reds believe that Bailey’s 2013 breakout was no fluke. While Bailey’s career up to last year had been somewhat inconsistent, that kind of price requires Bailey to keep pitching at the level he did last year. And there are reasons to think that he may very well do that.
Perhaps most important in his breakout was a sharp uptick in his strikeout rate, which went from 19.2% in 2012 to 23.4% last year. By ranking, he went from 27th in the NL two years ago to 8th in the NL last year, as even just a few points of strikeout rate can make a big difference. And strikeout rate is the kind of metric that seems somewhat impervious to fluke seasons. You can either get guys to swing and miss or you can’t, and we just don’t see too many Brady Anderson type seasons when it comes to pitcher’s strikeout rates. But how much of a strikeout rate spike can we really expect to carry over from one season to the next?
Bailey isn’t the only pitcher this question is relevant for, after all. The Orioles are hoping that Ubaldo Jimenez’s 25% strikeout rate in 2013 is far more predictive than the 18% strikeout rate he posted in 2012, and the Tigers chose to keep Rick Porcello over Doug Fister partly due to Porcello’s jump from a 13.7% strikeout rate to a 19.3% mark last year. The Indians are trying to figure out whether to sign Justin Masterson to a long term deal, and a large part of the question will come down to whether they believe in Masterson’s 2012 K% (17.6%) or his 2013 K% (24.3%).
So, let’s look at other recent K% spikers, and see how well they did after posting big strikeout rate gains from one season to the next. First, the top five starters in K% increase from 2010 to 2011:
|2010 to 2011||Anibal Sanchez||Cliff Lee||Doug Fister||Zack Greinke||Matt Garza|
Doug Fister is the only guy here whose improvement carried over entirely, as the other four all moved back to about halfway between their 2010 and 2011 strikeout rates. Even Zack Greinke, who had a staggering 8% improvement, moved back closer to his prior year level. It is important to note that regression towards the mean wasn’t regression all the way back to the prior mean, however; the new strikeout rate did move players to a higher level than they had been at previously, but not as high as they were in their big breakout year.
What about 2011 to 2012?
|2012 to 2013||R.A. Dickey||Max Scherzer||Ivan Nova||Edwin Jackson||Paul Maholm|
Two more encouraging examples here, as both Max Scherzer and Ivan Nova retained almost all of their strikeout gains from the prior year. On the other hand, Dickey and Jackson regressed significantly, while Maholm joined the group of pitchers who met in the middle. In general, the trend of regression proved to be more common, but in the last couple of years, there have been three examples of pitchers whose strikeout rates have not moved back towards prior levels after a big jump. It is possible to make a big jump forward in strikeout rate and keep those gains into the future, but it should be noted that that is not the norm, and most pitchers will see their strikeout rates move back towards something closer to their prior levels.
As an additional reference, here are the projected strikeout rates for the 2013 spikers, according to Dan Szymborski’s ZIPS projections, which account for multiple years of data.
Ubaldo Jimenez: 26%
Homer Bailey: 20%
Justin Masterson: 21%
Rick Porcello: 17%
Because Jimenez has a track record of striking out a fair share of batters earlier in his career, ZIPS sees him sustaining last year’s bump and continuing to miss a lot of bats in the future. For Bailey, Masterson, and Porcello, the system expects each to move back towards their prior levels, though each is projected to have higher strikeout rates than they did in 2012.
While it can be tempting to look at guys coming off a breakout year and ignore what came before it, history suggests that we almost always want to remember what the player was before the breakout, and temper our expectations accordingly. Some players really have established a new level of performance, but they’re the exception, not the rule.
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