Continuing onward with the interminable offseason, the Royals are said to be looking for starting pitching. For this reason, we've profiled guys like Mat Latos and Cliff Lee on this site. The Royals are also still interested in Ian Kennedy. If we're going to go after a guy who had a bad season, why not skip the guy with a qualifying offer attached and go with Doug Fister instead?
Fister is only ten months older than Kennedy and has had a better run than Kennedy in the past few years. Or, at least you could say that if it were 2014. Except for the age part. That part doesn't change. Regardless, something clicked in 2011 for Fister, and that began a three-year stretch of stellar play. If you'll remember, Fister once set the AL record for number of strikeouts in a row against our own Royals back in 2012. He was good. Fister was traded to the Nationals before the 2014 season, and he promptly cratered, leading up to a 0.2 fWAR performance last year.
There are lots of reasons why Fister's performance declined. There's the age thing, which always has to be taken into account. There's the declining velocity - he's seen about a 3 mph drop in both his fastballs over the past two years. That coincides well with his Nationals years. There's the usage difference - Fister increased his sinker usage at the expense of his other pitches during his time with the Nationals.
Which is it? Is it both? It's hard to tell. Fister was never a hard thrower; he threw about 89 during his two full years as a Tiger. The prevailing narrative is that Fister's velocity decline is to blame. Let's try to isolate the pitch itself. Using Brooks Baseball's classifications, we can look at the BA / SLG allowed by pitch type. From 2011-2013, Fister's "peak", he allowed a .279 / .387 BA / SLG on his sinker. In 2014-2015, he allowed a .259 / .380 line. Hardly different.
In fact, if you click around those two references to compare those two time periods of the sinker on some of the other metrics, it's tough to pick out a difference. The horizontal and vertical movements are fairly similar. A lot of the other metrics, like GB% and whiff rate, are also similar. The sinker itself, in terms of stuff, seems pretty much the same despite the velocity decline. Indeed, the sinker is Fister's most important pitch, so the foundation is there.
The problem is with Fister's other pitches. The most glaring difference is with the four-seam fastball. It's terrible. Awful. Horrible. No good. In 2014-2015, that is. Fister allowed a .226 / .338 line on the pitch in 2011-2013; that ballooned to .244 / .733 in 14-15. It appears not to be getting as much rise as before, so there is less of a difference between it and the sinker. It's just kind of a meatball now. Fister throws this pitch only 5-6 percent of the time, though, so it should not be the primary cause of his decline.
That leaves the curveball, cutter, slider, and splitter as areas on which to focus. The splitter is his primary offspeed pitch and tracks well in terms of movement with the sinker, so might as well focus on that first. From here on, I'll call 2011-2013 Fister "Before" and 2014-2015 "After". I'm tired of typing those years. Before saw a .248 / .375 line on the splitter; After saw a .318 / .437 line. There's a difference for sure. In After, hitters had an easier time making contact (whiff/swing down) and squaring up the ball when they did make contact (line drives up). There again is not much of a difference in terms of horizontal movement or vertical movement; everything tracks with the sinker.
I'll submit a hypothesis about the splitter; hitters don't respect the breaking stuff anymore, so they can prepare much more easily for the splitter. The curveball, cutter, and slider are the remaining pitches to examine. The curveball has seen a drastic decrease in After, so that's next.
Once upon a time, Fister's curveball was one of the best curves in the league on the strength of its incredible sink. In Before, Fister allowed a .194 / .293 line on the pitch; After has seen a .229 / .361 line. Whiffs were never a huge part of the curveball's strength (Fister got a lot of called strikes with the pitch), but hitters more easily made contact with the pitch in After. This looks related to movement changes. Fister's curve is getting a little less horizontal break and a little less vertical break, and it looks a lot like Pre-Before in terms of movement.
This is where usage comes in. In terms of usage, Fister's more similar to Pre-Before than Before. Pre-Before Fister wasn't very good either. He's lost something with his curveball. Maybe it's feel. Maybe he made some sort of grip modification to generate more contact. Maybe he doesn't like the pitch as much anymore. Regardless, that was his best pitch, and he lost it.
The cutter/slider are the other breaking pitches he has. Brooks has mostly the cutter in 2014 and mostly the slider in 2015. The slider is the one that shows the most difference in BA / SLG between Before and After. He's just not getting the drop on those breaking pitches either. He's having trouble keeping his breaking pitches down; each breaking pitch saw a decrease in ground-ball rate between Before and After.
Quick summary time. Fister's sinker/splitter combo likely retains its quality, but his breaking stuff is no longer getting the drop he needs. He's leaving breaking pitches up in the zone, and they're just not as good anymore. Fister's four-seam fastball is also a poor pitch, so he's left to rely on his sinker/splitter combo, becoming a much more predictable pitcher.
In order for Fister to regain his prowess, he absolutely must regain his curveball. A sinker/curve/splitter Fister can throw out the four seamer, cutter, and slider as change-of-pace pitches. Because he retains his sinker/splitter combo, he can still get lefties out at a decent rate. Without a viable breaking pitch in which he feels confident, righties smashed him in 2015.
So, how do you feel about velocity vs. stuff? Do you care more about a 3mph drop in velocity or a lack of breaking stuff? I doubt Fister can regain much velocity, though he did have a trip to the DL in 2015. He steadily regained velocity after he came back but was switched to the bullpen in August due to poor performance. How the Royals answer these questions determines if Fister's on their radar. If Dave Eiland and Co. think they can fix his curveball, Fister could be a huge bargain. If Fister's curveball is gone forever, then he'll have to find a way to succeed in the bullpen in order to remain a major leaguer.