Reviewing the 2015 Spring K% Surgers & Breakout Candidates

Review season continues and today I’ll recap the starting pitchers whose spring training strikeout rates were significantly above their Steamer projected K% marks. As a reminder, with the help of Matt Swartz, I found that spring strikeout rates do provide meaning with regards to regular season performance, something that Dan Rosenheck validated as true more recently.

The original list of candidates:

Though Michael Pineda did miss some time with injury, he did still manage to just barely surpass 160 innings pitched. And while his ERA jumped above 4.00 for the first time in his short career, his his strikeout rate did rebound closer to his rookie year mark. His fastball velocity increased slightly, though having moved further away from shoulder surgery, the hope was that we would see a more dramatic rise. That said, both his fastball and cutter induced more swinging strikes, which helped boost that strikeout rate.

Another season in the books, and another tease from Nathan Eovaldi. Sure, his strikeout rate did increase and beat Steamer’s projection, but we still dream for higher. He did add that splitter to his repertoire and it was pretty darn good, generating a 16.3% SwStk%. And as Eno mentioned in his bold predictions recap, when he started trusting it more in the second half, his strikeout rate jumped to 20.7%. That’s still far from exciting, as his slider was poor and despite the high velocity, his fastball just isn’t good at generating whiffs. But at least we’re witnessing some positive steps, even if they’re of the baby variety.

Chris Tillman’s ERA actually ended up dropping for the second straight year, as this time he couldn’t lean on good BABIP fortune and luck stranding runners to suppress it, despite his usual mediocre skills. And for the first time, none of his pitches generated a SwStk% in the double digits.

How Jered Weaver was able to generate a strikeout rate over 20%, whether the games counted or not, is pretty shocking given how much his fastball velocity has fallen. It came in at just 83.3 mph this year, a full three miles per hour less than last season. So naturally, his strikeout rate fell precipitously and his ERA climbed over 4.00 for just the second time in his career, and first since 2008. Unless he can miraculously find that lost velocity, he may very well be done as an effective Major League pitcher.

Despite a decline in fastball velocity, James Shields combined a move to the National League plus a higher rate of swings and misses on nearly all his pitches to set a new career high in strikeout rate. At age 33, I’m not sure how he did it and would bet against a repeat. Since expected improvement in his HR/FB rate is simply going to be offset by a drop in his LOB%, he’s not really going to be undervalued next year, even after posting his highest ERA since 2010.

Taijuan Walker didn’t exactly enjoy the big breakout some were betting on after his spectacular spring training. But that was mostly just bad luck, as he suffered from an inflated HR/FB rate and suppressed LOB%. Despite possessing a mid-90s fastball, he hasn’t yet translated his heat into an elite strikeout rate. It could still happen at anytime though.

Collin McHugh was a tough pitcher to project. With little Major League experience and solid, albeit unspectacular, minor league strikeout rates, how much should we have believed his 25.4% strikeout rate in 2014? Not surprisingly, his strikeout rate regressed this season, primarily due to a slider that lost some of its ability to induce swings and misses.

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While the two studies linked to in the intro have proven that spring strikeout rates do infer meaning, we still have to remember we’re dealing with tiny samples. So a spring strikeout rate surge along certainly shouldn’t be used as justification to expect a breakout, but is a good piece to use as a tiebreaker if choosing between two pitchers. Eight of the twelve pitchers did indeed outperform their Steamer projected strikeout rates.