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What do the Oakland A’s have in Santiago Casilla?

Tracking the growth of the A’s newest reliever since he was last an Athletic.

Since leaving the A’s, Santiago Casilla has been a different player. That’s not a joke about his name (now it is!), he transformed as a pitcher across the bay. What do the A’s have in their newest reliever?

He’s developed a two seam fastball

Before departing from the A’s, Casilla was a straight fastball heavy pitcher, throwing his four-seam offering over 60% of the time. That held steady when he first arrived in San Francisco, but in his third year there, he started to throw a two-seamer (also considered a sinker by some). He still threw his four-seam fastball a significant amount (35%) but slowly phased it out in favor of the two-seamer, dropping his four-seam usage as low as 15%, routinely throwing his two-seamer over a third of the time.

What effect did that change have? Predictably, Casilla has generated more groundballs, getting as high as 56.3% in 2014. For comparison sake, Kendall Graveman generated a 52.1% groundball rate last year. It’s not extremely high for a reliever, but groundballs are better than other means of contact and that amount is notable.

He’s was consistently awesome in San Francisco*

For seven straight years, Casilla was a reliable reliever in late game situations. In his time in SF, Casilla’s total ERA was 2.42. He struck out a respectable 8.3 batters per nine innings, averaged just .7 home runs against per nine innings pitched, and held an impressive 1.16 WHIP.

There are some worrying factors - Casilla’s control can leave something to be desired. He gave up an average of 3.5 walks per nine innings pitched, which led to a FIP a full run and change higher than his ERA. At 3.56, that FIP leaves Casilla looking like a merely average reliever.

There are two schools of thought with those numbers in mind. The first is the optimistic one, the idea that there are players who can consistently outperform their FIP, and that with seven or so years of doing so, Casilla is one of those players. There are reasons to believe it - his exit velocity (which is only available the past two years, meaning it misses Casilla's best years) has been 2.4 MPH slower than league average. A way to beat FIP is to induce weak contact, and Casilla might have that skill.

The other side of the fence is that Casilla had factors in SF that would make his standard numbers look better than he really deserved. For one, the Giants have one of the more pitcher friendly parks in the league. In 2015, it was actually the most pitcher friendly, and it’s typically the hardest place to get a ball out of the yard. The leads to two thoughts - 1) damn, Barry Bonds was a monster and did all the steroids, and 2) that doesn’t bode well for Casilla in a new stadium. A park in which it’s virtually impossible for a lefty to hit a bomb would probably inflate a righty like Casilla’s stats, right?

File this one away under baseball is stupid. Casilla has been essentially the same pitcher home and away, putting up only slightly worse numbers on the road over the course of his career, and actually giving up fewer dingers away than at home. For whatever it’s worth (and seriously, I don’t know what that’s worth), Casilla’s numbers don’t indicate he’s a product of an extreme park.

Casilla’s new home isn’t particularly offensive either, and many of his games will be played in other offensive suppressing stadiums. That’s the good news!

The bad news is that the dudes behind Casilla will be different next year than they were with his previous team. Say what you will about the Giants (just don’t say it in front of children), but they could pick it with the best of them. The A’s? Not sure if you’ve heard, but they couldn’t.

There’s reason to believe the A’s will be better in that regard in 2017, whether that be due to new personnel, or be it due to the old notion that there’s nowhere to go but up. No matter how much the A’s improve in 2017, though, they probably won’t be up to par with what Casilla got accustomed to in SF.

*So what happened in 2016?

Casilla was consistently good except when he wasn’t. He wasn’t in 2016. Why was he so bad?

For one, a lot of his trouble came in spurts. He was great in April and May, terrible in June, fine and July and August, and terrible in the final two months of September and October. There’s danger in diving too deep into splits, and we shouldn’t make too many specific takeaways about what that month by month breakdown means.

That said, Casilla's early success and the subsequent months of acceptable pitching shows that at least at times, Casilla has the stuff needed to succeed. How’s that stuff looking?

Velocity wise, there’s no reason to be worried. Casilla’s fastball velocity actually increased last season, as did his two-seamer’s. He saw a late season dip in velocity, but that’s to be expected. It could be a bad sign, but Casilla’s trouble preceded that loss, and most pitchers lose velocity in the waning months of the baseball year.

From a movement perspective, things were mostly good for Casilla in 2016. His pitches moved more than they did the year previous, with the exception of his two-seamer, which sunk less. That resulted in fewer groundballs than he saw in 2015, but not by a huge margin. His flyball and linedrive percentage increased but only a small amount.

His spin rate increased in 2016, too. Both are proxies for stuff and health, which by and large look good. There’s of course much more to pitching than those two things, but by those measures, it’s strange to see Casilla struggle so mightily.

So where did Casilla go wrong?

It wasn’t a fluky, weak contact thing thing. His hard hit percentage went up last year by five full percentage points and change. That’s undoubtedly a bad thing, something that can’t be blamed on defense or luck, it’s purely on Casilla.

That increase in hard hit percentage is reflected by, well, the speed with which his pitches were hit, a three percentage point bump last year. Batters hit flyballs almost 7 MPH faster in 2016 than 2015, which resulted in a HR/FB that reached a career high at 15.1%. The worse ERA isn't a product of weak contact finding holes.

To summarize! The increase in exit velocity (and bad contact) is the how, but we still don't know the why. Casilla's velocity didn't decrease, nor did his spin rate or movement. His location was roughly the same, and he wasn't pitching behind in the count at a higher rate. He wasn't unlucky, clustering hits with runners on base, nor did he give up more hits on dinkers or squibbers. Essentially, ¯\_(ツ)_/¯.

What the A’s have in Casilla

Casilla fits right in with the theme of the offseason, a low cost, short contract guy who is capable of goodness. There are reasons to worry that he’s lost his effectiveness, and there are reasons to think he can be the sub 3.00 ERA guy he was the majority of his stay in SF. For the price, he makes sense and the low risk, medium-high reward nature of deal makes sense in the grand scheme of this particular offseason.