Archive for strikeout rate

In last episode’s thrilling cliffhanger, I left you with a formula that I brashly proclaimed “does a great job of explaining the trends” in strikeout rates for meetings between specific groups of batters and pitchers.  Coming up with a formula to explain what was going on wasn’t pure nerdiness — making formulas to predict these results is the point of this research project.  You see, the goal of my FanGraphs masters is to come up with a system by which we can look at a batter and a pitcher, and tell you, our loyal followers, some educated guesses of the chances of pretty much every conceivable outcome that could result from these two facing off against each other.  Getting a sense of the expected strikeout rate is merely the first step in what will likely be a long process of continuous improvement.

The idea of this matchup system is to not only give you estimates that are more free from the whims of randomness than “Batter A is 8-for-20 with 5 Ks and 1 HR in his career against Pitcher B,” but also to provide some evidence-based projections for matchups that have never even happened.  How do we propose this can be done?  By looking at the overall trends and seeing how players fit within them.  Can it really be done?  It definitely looks that way to me.  Today’s installment will be about attempting to convince you of that.

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Though it’s quite brief, I have to believe that Jeff Sullivan’s post on the correlation between pitcher contact rates and strikeouts from this past August has got to be one of the most exciting of the year. It makes so much sense — miss bats, get strikeouts — and yet Mr. Sullivan appears to be the only one on the interweb (besides our own Matthew Carruth) asking substantive questions about it*.

*If there are others, please don’t hesitate to mention them below.

You can see the correlation between the two in this image I’ve stolen directly, unforgivably from Lookout Landing:

That’s pretty striking. And it begs a question: If the correlation between Contact% and pitcher strikeouts is so strong, then couldn’t Contact% help us understand which pitchers might be poised to top the strikeout charts next year?

Yes. With some caveats.

In that same post to which I’ve linked above, Sullivan also notes that, beyond Contact% (league average 80.5%), pitchers also control their strikeout rates by other means, such as First-Pitch Strike% (league average 58.2%), Zone% (league average 49.3%), Called Strike%, etc. While none of these factors correlate as strongly as Contact% to pitcher strikeout rates, it does appear as though they’re not entirely negligible, either. To that end, I’ve included the first two of those below for comparison’s sake.

What happens when we run the 2009 numbers for Expected K%s (xK%)? That’s the question I asked myself — and which I answered, I think, by means of the kinda dumpy looking table you see below. Here are the Top 10 starting pitchers (50+ IP) by Contact% with expected and actual strikeout rates, plus K/9:

So, what do we see here? Some likely suspects, for sure: Harden, Lincecum, Vazquez, de la Rosa. But also some surprises: Felipe Paulino (second!), Gio Gonzalez (third!), and Bud Norris. The first two of those guys I wrote about last week as tRA* surprises. Bud Norris I didn’t mention, but he actually finished 66th in tRA* out of the 183 pitchers with 150+ xOuts.

What conclusions can we draw from this? Well, we should probably be careful about that, as more research needs to be done in this area. Still, it’s probably reasonable — given his xK% and overall profile — to expect at least a small improvement in strikeouts from Felipe Paulino. Moreover, there’s reason to think — given his excellent Zone% — to think that Bud Norris will probably turn some of his walks into strikeouts.

How well do you think Norris will perform in 2010? Enter your Fan Projection here.

In order to cope with the loss of two starting pitchers from last year’s club, the Twins imported veteran starter Livan Hernandez to fill innings at a reasonable clip. At this point in his career, though, it was clear that Hernandez wasn’t going to be much more than a pitch to contact innings eater. Well, he’s lived up to that persona and then some.

A guy who posted average strikeout rates in his prime is now transitioning into the second stage of his career as the new Nate Cornejo. His K/9 this year stands at a paltry 2.83, second lowest in baseball among starting pitchers. Only Jon Garland, who we discussed previously, is missing bats with less frequency than Livan Hernandez. In fact, both Garland and Hernandez are posting remarkably low strikeout rates compared to recent history.

Since 1988, only 17 pitchers have tossed 100 or more innings in a season with a K/9 of 3.00 or less, combining to make it happen 22 times. Kirk Rueter was the last to do it, pitching himself out of baseball in 2005 with a 2.10 K/9. The previously mentioned Cornejo did it in 2003, but only lasted 25 innings into the 2004 season before seeing his career end as well. Clearly, this isn’t a list of guys who went on to have long, productive careers after watching their ability to rack up the strikeouts all but disappear.

However, Hernandez has managed to succeed despite the strikeout rate by dramatically cutting down on his walks and keeping the ball in the yard. In all, he’s actually posting a not horrible 4.46 FIP, and while he probably won’t be able to keep his home run rate this low, that he’s not walking anyone should give the Twins hope that he can squeeze together a few more months of useful pitching. Hernandez isn’t a guy you want in your rotation long term, but given the choice between paying Carlos Silva $48 million over four years or paying Hernandez $5 million for one year, it seems pretty clear that Minnesota made the right choice.