Spring's Gleanings: spring training strikeout and walk rates

With just two Cactus League games remaining, the Mariners have very few roster decisions left to make. The pitching staff is set and the last remaining position battle is between Steve Clevenger and Rob Brantley for backup catcher. There is very little time to learn anything more about the players who will make up the 2016 team. For the most part, spring training statistics can be tossed by the wayside. There just aren’t enough plate appearances or innings pitched for most stats to become predictive—except for pitcher strikeout and walk rates.

A few studies have been completed showing the predictive value of spring training strikeout and walk rates. And based on what we know about sample size stabilization points, strikeout and walk rates are some of the earliest peripheral stats to stabilize. These stats still have to be taken with a grain of salt because of the quality of competition and the nature of spring training. Many pitchers are working on new pitches or new approaches and may not be throwing with maximum effort. With all that in mind, let’s see if any of the Mariners’ pitchers showed any significant increase or decrease in strikeout or walk rate this spring.

*I limited my query to pitchers who faced more than 50 batters.

Simply looking at his K/BB ratio, it looks like Taijuan Walker is primed for a breakout year. Last year, both his strikeout rate and walk rate trended in the right direction despite a rough first half that drove his ERA much higher than his FIP. This spring, he’s maintained those improvements. Of course, Walker’s true test will be to find a way to keep the ball inside the park.

On the other end of the spectrum is James Paxton. His velocity took a steep dive this spring and his strikeout rate suffered. He walked more batters than he struck out this spring which is never a good sign. He’ll start the year in Tacoma and we’ll want to monitor his velocity and his strikeout rate to see if this spring was a minor blip in his career or a sign of things to come.

There was a reason Donn Roach was turning heads in camp as a non-roster invitee. He was striking out batters at a rate higher than almost any other time in his career. In fact, you have to go back to 2012 to find a strikeout rate anywhere near the 24.2% he put up this spring, and that was in Single-A ball. Not only was he striking out a ridiculous number of hitters, he also hasn’t given up a single walk this spring. With the acquisition of Nick Vincent, the Mariners’ bullpen is set but Roach will be waiting in the wings, ready to prove that these gains are for real.

The drop in strikeout rate from Hisashi Iwakuma is a little concerning considering the health issues that allowed him to return to the Mariners. He also faced the least amount of batters in this sample so we should take his stats with an even larger grain of salt than normal. The good news is that he’s been throwing without any discomfort or setbacks this spring and all signs point to a healthy start to the season.

Among the relievers who faced less than 50 batters, there were a few performances that stood out. Tony Zych struck out almost half of the batters he faced this spring while only walking one. Moving to the bullpen didn’t immediately boost Mike Montgomery’s strikeout rate. His velocity has been much higher and he didn’t make the transition until later in the spring so we could still see a jump in strikeout rate during the regular season. Joel Peralta struck out almost a quarter of the batters he faced this spring which helped him secure a spot in the bullpen.