Encouraging Opening Week for the Back of the Starting Rotation
While it’s still too early in the season to separate the signal from the noise, I think one fact from the Brewers’ first week is particularly encouraging: The pitchers at the back of the starting rotation, who each came into the season with significant question marks, are off to a hot start.
Wily Peralta, Chase Anderson and Jimmy Nelson combined to pitch 458 2/3 innings for the Brewers in 2016 and posted a combined 4.61 ERA (about half a run per game worse than the National League average), with peripheral numbers suggesting they could and perhaps should have been even worse. Through the first trip in the rotation in 2017 this same trio has worked a combined 17 innings and allowed just two runs against two very good offenses, the Rockies and Cubs.
All of the usual caveats about small sample sizes apply here. With that said, I do think there are some factors that are interesting, if not instructive, regarding this group’s early results:
Wily Peralta’s Fastball is Faster
Before I dig into this, a disclaimer: There has been a change in the way pitch speeds are measured across Major League Baseball in 2017. Velocity is now measured as the ball leaves the pitcher’s hand, as opposed to at a point 50 feet from home plate. It isn’t entirely clear how much difference this will make, but Jeff Sullivan of FanGraphs recently went through the data and suggested the average pitcher’s listed speed is up somewhere around half of a mile per hour.
Even taking that adjustment into account, however, Wily Peralta’s average fastball from his first appearance (96.5 mph) is up significantly from his averages in 2015 and 2016 (94.3 and 94.8 mph, respectively). Peralta’s pitch speed is a topic we’ve discussed before: In fact, one of the very first editions of The On Deck Circle highlighted it as a key for his 2016 season. It did not improve in 2016, and his results didn’t get better either. Early this year, however, we’re seeing signs that it could be back.
Chase Anderson Trusted His Fastball a Little More
As Sullivan’s data would suggest it should, Chase Anderson’s fastball is (perhaps artificially) registering a bit faster in 2017, coming in at an average of 92.1 mph in his first start compared to 91.1 in 2016. What’s interesting, however, is that he used it a little more often than you would expect. FanGraphs’ data from his first start showed that he threw a four or two-seam fastball on almost 70% of all pitches on Thursday, compared to around 57% a year ago.
Anderson only threw 88 pitches on Thursday so the difference in fastball usage at this point is about eleven pitches over the course of his outing, roughly one additional fastball to every other hitter. Sample size could be a factor here, but it’s also worth noting that the Brewers’ pitching coach and entire catching corps have all turned over in the last 18 months or so. It’s reasonable to believe that this could result in subtle changes in emphasis or pitch mixes for various Brewers hurlers.
Jimmy Nelson’s Mix of Pitches is Changing
If the FanGraphs data from Jimmy Nelson’s first start is any indication, we’re going to see more changeups and fewer curveballs than we’ve seen from him recently in 2017.
The data suggests that Nelson has shaken up his arsenal a couple of times in his career, but he’s never really focused on a changeup very often: It’s represented around 2% or less of all the pitches he’s thrown from 2013-2016. That makes it all the more interesting that he appears to have thrown the pitch eight times in his solid outing on Friday.
At the same time, Nelson’s best season in 2015 coincided with the addition of a curveball, which he threw around 20% of the time, to his arsenal. He’s since gotten away from that pitch, and also only threw it around eight times on Friday. These two pitches have similar velocities so it’s possible that pitch classification mistakes could explain some of the change, but it’s also possible that we’re seeing the start of another shift in Nelson’s tendencies.
Peralta and Anderson are expected to take the mound Tuesday and Wednesday of this week as the Brewers head north to take on the Blue Jays, and Nelson’s spot in the rotation will be due up when they open a series in Cincinnati on Thursday. It will be interesting to see if any of these early trends continue in their second starts.