On Marcus Stroman and strikeouts

It is a truth universally acknowledged, that a pitcher in possession of good stuff, must be in want of a high strikeout rate.

— Jane Austen on baseball, probably

Tomorrow marks six months since the Blue Jays traded Marcus Stroman in the lead up to the trade deadline. Since I didn’t get around to putting together thoughts on the deal at the time, I thought it would be an opportune time to finally do so, especially now that there’s some distance and sentiments aren’t quite so inflamed.

But before that tomorrow, I want to finally publish something that will be somewhat related, and that’s been a long time coming. In fact, this very post was created in August 2016, and even then it was something that had been mentally percolating since the end of Stroman’s first season. So this is about five years in the making (it was supposed to follow another project I’ve never got around to finishing, alas). It’s about Stroman and his strikeouts (or perhaps lack thereof).

Back in late May 2014, when the Blue Jays recalled Stroman to join the rotation only a couple weeks after after sending him down following his initial stint, I distinctly recall being against it. While his AAA results were very good or even excellent (3.03 ERA in 35.3 innings, 45 strikeouts), in following those outings I had recalled him getting to a lot of two strike counts but not putting batters away. I wanted to see some progress on this point before bringing him back up, a little bit more polishing, lest it ultimately be something exploited by big league hitters.

On one hand, shows what I know; Stroman was immediately an above average starter. On the other hand, there was (and is) something to my contention. For as filthy as Stroman’s stuff — recall this Fangraphs article from February 2015 with notional comps to Roy Halladay’s sinker, prime Johnny Cueto’s four seamer, the late Jose Fernandez’s curve and Chris Archer’s slider — he’s never struck out many batters.

Or at least as many as what that kind of raw stuff should imply, hence the above aphorism. Strikeouts aren’t the only way to succeed of course, but the best pitchers with the nastiest stuff tend to record a lot of strikeouts. Looking at pitchers with 500 innings since 2014 when Stroman debuted, the relationship is clear (Stroman is highlighted as the red triangle):

So I’ve always been curious about digging into the components or determinants of Stroman’s strikeout rate. After all, a strikeout requires at least three pitches, so if a lower strikeout rate is a by-product of generating more weak contact on the ground early in the count, that’s not a bad tradeoff. On the other hand, if it’s a reflection of not putting the batters he does get to two strikes away, that’s an actual issue.

As a Blue Jay, Stroman faced 3,285 batters (excluding a couple were walked intentionally or reached via interference). If those, 1,318 (40.0%) put the ball in play on or before the third pitch excluding 0-2 counts. League-wide, this was about 36%, so Stroman was inducing significantly more early contact.

More importantly, he made hay off that early contact. For example, in recent years when putting the first pitch in play batters hit about .350 and slug about .600. Career Stroman has held them to a .317 BA and .456 SLG, resulting in about six more singles, but eight fewer doubles/triples and nine fewer home runs in under 400 at-bats than a league average pitcher would. All told, batter putting the ball in play early against Stroman have hit .336 and slugged .502, compared to about .340/.580 overall.

At least on a relative basis then, early contact has served Stroman well (it’s worth noting in absolute terms, it’s still poor; all else equal if every batter put the ball in play early or on the first pitch, Stroman would not have good results). That means we need to adjust Stroman’s strikeout for opportunity. Stroman’s 19.3% overall strikeout rate with the Jays works out to about 9% below league average — but as a percentage of batters who didn’t put the ball in play early it’s 32.3% compared to about 33.8% for the league. That’s only about 5% below average, roughly halving the gap.

Next to examine is 0-2 counts, the simplest two strike counts to analyze. Stroman put 615 batters in an 0-2 hole, or 18.7% of all batters compared to 20% for the league. That slightly smaller rate tracks with his higher proportion of balls in play, so it’s a knockon effect rather than deficiency. But critically, Stroman was more proficient at finishing off these batters, with a 16% whiff rate and 66% contact rate, compared to 14% and 73% league average. Those that did get the ball in play fared even more miserably than the league overall (.120 BA/.200 SLG vs. ~.150/.225).

It’s a similar story at 1-2, Stroman gets in slightly fewer of the counts relative to league average, with a slightly lower contact rate (73% to 75%). At 2-2 counts, he’s basically right in line with league average in terms of the batters he gets there, and the rate at which he puts them away. Interestingly, batters putting the ball in play in these counts did a little better than league average against Stroman, although still miserably (under .500 OPS in both counts in both cases).

Overall then, the conclusion is that looking at raw strikeout rates somewhat underestimates Stroman’s prowess at striking batters out. Because he was so good at generating weak contact, fewer batters were in a position to strike out against him, but he was a little better than average at finishing them off when he did put him in a hole (and the deeper the hole, the better at finishing them off compared to average).

There are a couple open questions. First, could Stroman’s appraoch be optimized? He’s generates much weaker contact than average early, but overall first pitch and 1-0 contact is still pretty good. Could he trade off some efficiency for a higher level of effectiveness?

The second brings us full circle. Why does a pitcher with such good stuff not miss more bats? Overall, his contact rates are worse than average, year in and year out. To some extent, it’s definitely a choice and choosing to generate (mostly) weaker contact, with an an ability to dial it up when it matters most. But one wonders if there’s an even better version of Stroman in there.