In the search for solid big league bullpen pitchers, teams often look to starters in the minors, especially when their rotation is already set. This gives young guys big league experience without adjusting the rotation’s schedule. Most teams aren’t going with a six-man rotation anytime soon, so they have to find ways to get their prospects some experience.
The Philadelphia Phillies have done that by seemingly converting starting pitcher Seranthony Dominguez, who never relieved more than four games in a single season with exception to 2014. The change isn’t due to poor performance as a starter as he only had one season where he posted an ERA above 3.50.
However, it should be noted that he did have some arm injury issues, so that’s more likely the reason than anything else. It is somewhat surprising, though, as he finished last year in High-A and started this season in Double-A, so he has really moved up fast.
Though, the change to full-time reliever seems to be paying off. Since his call up in the first week of May, he’s posted a minuscule 1.61 ERA and a FIP of 1.75, and a SIERA of 1.83 which is, currently fifth among all qualified relievers. Another stunning statistic is the fact that both his hard and soft contact rates are sitting at 23.4 percent, which is crazy when most of your innings come in high leverage situations.
The only glaring issue I see is a home run per flyball rate of 6.3 percent when the league average for relievers this year is 11.5 percent. There’s no doubt Dominguez is excelling at limiting home runs in an increasing home run friendly time, so that’s really the only significant change to any of his numbers that is more likely than not to occur. Despite that his xFIP is only 2.33, so even if he gives up more home runs, closer to league average, his ERA and FIP will still be well below the typical reliever.
The one statistic that I still cannot wrap my head around is that he has yet to allow a single hit off his slider or changeup, which accounts for nearly 30 percent of all the pitches he’s thrown. Between his secondary pitches and his fastballs he has a wOBA of .171, which is simply incredible. Normally you see a reliever who is really solid with limiting base hits or home runs or keeping runs off the board, but Dominguez is really doing it all.
While we’re dealing with a small sample size of 22.1 innings so far, at some point if these numbers don’t change significantly we may just have to accept that he is this good. Whether or not that will happen we’ll have to wait and see.
Leaving his future performances out of it, this stellar start to a big league career couldn’t come at a more perfect time for the Phillies as they recently optioned long time Phillies reliever Hector Neris, who closed for the team both this season and last. But after a horrible start to this season, a change was in order.
According to The Morning Call, a local newspaper in Allentown, Pennsylvania, the Phillies will utilize the closer-by-committee approach given the number of successful relievers they have. There’s not much doubt Dominguez will be a part of that, as he’s been solid in save situations. In fact, he’s been perfect—three saves and and nine holds in twelve opportunities.
I mentioned his run-based metric numbers as well as various averages against, but his peripherals are just as eye popping. A strikeout rate over 35 percent, good for 12th among relievers and a walk rate under four percent, which is 13th in the league. It will be interesting to see if he gets the lion’s share of closing opportunities with all the numbers I have mentioned so far.
The reason his walk and strikeout numbers are so good is the fact that his swinging strike rate seems to continues to increase, so the limited contact he allows is increased by inducing more swings and misses.
From everything I’ve seen, Dominguez’s success is due to how well he’s locating his pitches, particularly the fastball as well as how hard it is to differentiate between his pitch types. The chart below shows the top and side views of all four of his pitch types and how similar they look right up until about 15 feet from the plate. This is the ultimate recipe for total dominance.
Seranthony Domínguez, 98mph Fastball & 88mph Slider, Overlay. pic.twitter.com/Z7qPHk8jjS— Rob Friedman (@PitchingNinja) June 10, 2018
Furthermore, the slider is really the linchpin here; it’s absolutely devastating. Although it doesn’t get a ton of traditional movement, it’s more like a curveball that just bottoms out at the last second causing batters to swing in embarrassing fashion.
I mentioned how well he’s locating his pitches, but more specifically it’s a veteran-like ability to locate his fastball on the sides and bottom of the strikezone which has earned him a 20.5 percent called strike rate out of 200 four-seamers thrown.
The way his pitches “tunnel” right up until they’re basically on top of the hitter, plus an ability to locate the fastball on the edges to earn called strikes, have given Dominguez the perfect mix to put up the numbers he has thus far. There doesn’t seem to be a single hole anywhere in his pitching, so for an age-23 reliever who was initially a starter, he’ll likely get even better than he is right now, as hard to believe as that may be. If I’m the Phillies, he instantly becomes my closer.