May has always been a useful milestone in the baseball season to peruse the early stats -- see who was hot, who was cold, and to speculate about the reasons. And one stat in particular that stands out among the Tigers is the strikeout rate of Joakim Soria.
After a seven-year career of striking out 9.8 batters per nine innings, Soria has only recorded 5.4 strikeouts per nine so far in 2015. Instead of striking out every fourth batter (and more), he's now only striking out one out of every six. He has induced swings-and-misses in general at less than half the rate of his career average. This drop in strikeouts is the basis behind his 3.55 FIP and 3.95 xFIP in the face of his minuscule 1.54 ERA.
It's only natural to wonder why we've seen such a steep drop, and to be surprised that such a negative change correlates with great overall results. After all, who cares how many batters you strike out if you're perfect in save opportunities and allow 0.60 baserunners per inning? Still, curious minds want to know whether this change is here to stay, and if it bodes poorly for the future.
Investigating Soria's batted ball profile reveals one possible cause: an increase in fly balls. After inducing flies in about 34 percent of batted balls since his second Tommy John surgery in 2012, Soria has upped that rate to 39 percent this year. That may seem like a minor difference, but fly balls fall in for hits about 12 percent of the time, as opposed to line drives -- which Soria has reduced in the process -- find a hole about 70 percent of the time.
The increase in fly ball rate could be the result of an increase in fastball usage. Over the last six seasons, Soria consistently used his fastball 67 percent of the time. So far this season he's thrown the heater over 82 percent of the time, and opposing batters are hitting only .103 against it. Not only has he thrown the fastball more often, he has also induced fly balls with it at a higher rate, finally reaching the levels he showed prior to the surgery.
One month into the season we're still dealing with small sample issues in all of the statistics, and that caveat goes double for relievers. That said, it's not too early to start looking for tangible changes and picking out new patterns. Soria hasn't struck out many batters, and he's been dominant all the same. He's been using his fastball a lot more, and he's also been inducing more fly balls. The relationship between all these factors isn't clear yet, and we don't know whether this is a change in approach that will continue in future.
Soria has probably thrown so many fastballs because chilly temperatures didn't allow him to grip his breaking pitches as well as he'd like. Or maybe because he's faced a bunch of hitters who are vulnerable to high heat. Or simply because the fastball was working, so he stuck with it. But maybe, just maybe, we're seeing a new Joakim Soria. One that, at least so far, is just as dominant as he always was, but in a completely different manner. Either way, it's something to keep an eye on.