Hector Neris’ Nasty Splitter and Sustainability

The Phillies are off to a really good start this season, sitting at 16-12 in what is expected to be a rebuilding season as the team finally separates itself from its former glory in a move to the future. The team has some exciting young pitchers already succeeding in the majors with Vincent Velasquez and Aaron Nola putting together some very good performances. Maikel Franco is a promising young hitter and J.P. Crawford should be ready to contribute at some point. To get to their record this season, the team has succeeded by limiting runs and winning close games. The starting pitching has led the way, but the bullpen has been key, as well. No pitcher has surprised more than Hector Neris, who has upped the use of his splitter and gotten fantastic results.

So far this season, Hector Neris has faced 63 batters and struck out 27 of them. If you look at the strikeout-rate leaderboard for relievers who’ve recorded least 10 innings, you find that Andrew Miller, Dellin Betances, and Craig Kimbrel are the first three names to appear there, which isn’t surprising. Hector Neris is fourth, which is. The Phillies reliever struck out more than a batter an inning last year, but has taken that performance to new heights this season. Neris’ secret is out, as he has increased his splitter usage from 21% last season to 52% this year.

Over at MLB.com, Mike Petriello already took a really good in-depth look at Neris’ splitter (darn him for getting there first and doing it fantastically). Petriello discusses what makes Neris’ splitter so effective: it’s fast with low spin, features a big drop, and looks like the fastball out of his hand. The results have been pretty crazy, as Petriello notes:

Since the start of 2015, Neris has thrown the splitter 292 times, and allowed six hits on it, collecting 42 strikeouts — which is a .092 average. It’s been so dominant that if we look at the seasons (since 2008) with the highest percentage of swinging strikes on the splitter, Neris actually shows up twice.

Highest swinging strike percentage, splitter, 2008-16

1. Manny Parra (2013) — 69.8 percent
2. Brandon League (2009) — 67.4 percent
3. Neris (2016) — 62.5 percent
4. League (2010) — 51.1 percent
5. Neris (2015) — 52.5 percent

Hector Neris doesn’t pitch in the zone, but hitters swing anyway — and they often miss. The table below shows Neris’ plate-discipline numbers this season and his ranks among the 132 relievers with at least 10 innings pitched.

Hector Neris and Hitters’ Lack of Plate Discipline

	PITCHf/x%	Reliever Rank
Zone %	38.7%	128
O-Swing %	46.5%	2
Z-Swing %	55.7%	121
O-Contact %	34.3%	2
Contact %	57.8%	3

Only four pitchers (Marc Rzepczynski, Brad Ziegler, Luke Gregerson, and T.J. McFarland) have recorded more pitches outside the zone than Neris. He’s been effective, however, because he’s also found success with that approach. Only Andrew Miller has induced more swings outside of the strike zone, and only A.J. Ramos has allowed less contact on swings outside the zone.

Hitters should know what’s coming. In striking out the side against the Cardinals on Tuesday, Neris threw 15 total pitches. Of those, 12 were splitters, eight of them out of the zone. Even when the pitch is in the zone, however, it remains difficult to hit. Neris threw three splitters to Brandon Moss, getting to a 1-2 count and close to the final out of the inning. After a high fastball, Neris finished off Moss with a splitter in the zone.

Perhaps due to pitching so much out of the zone, he has kept hitters off balance enough that, when he does pitch in the zone, hitters don’t swing, leading to called strikes.

The splitter also appears to cause hitters to become late on the fastball, which itself is in the low- to mid-90s. Such a thing appears to have happened to David Wright, for example. Neris got strike one on a two-seamer, then went to 0-2 by getting a swing and a miss on a splitter out of the zone. Neris then doubled down on the splitter, but Wright took the pitch. Neris then threw a fastball right down the middle.

While Neris’ splitter is itself a great offering, the sheer frequency with which he throws it — more than 50% of the time — is uncommon for a pitcher. Even for a reliever. Increasing it in the early part of the season has not hurt its effectiveness. Neris produced a 29% whiff rate last year and a 32% mark so far this season, per Brooks Baseball. Due to that frequency, it’s fair to wonder if he can keep this up and remain successful. While, of course, it’s unfair to expect quite this level of dominance, Neris has room to decline down a little and still remain a very good reliever.

Since 2011, there have been just 10 seasons during which a reliever used the splitter at least 40% of the time and reached 40 innings. Those ten seasons are split between just four pitchers: Koji Uehara, Zach Putnam, Edward Mujica, and Jose Arredondo. These are those ten seasons.

Any group with Uehara is going to look good. Mujica has had some solid seasons. Putnam has had one good year with one less so, while Jose Arredondo could not limit walks on his return from Tommy John surgery. When looking at single seasons of relievers, it can be tough to discern any sort of pattern. Reliever seasons can be subject to all sorts of small samples that might not represent a talent or be predictive of any sort of future. For Uehara, 2014 could be an outlier or taking the roughly 180 innings as a whole might be more representative.

By combining all of the seasons above, we might be able to draw some conclusions. The chart below has three rows: the first row shows the ten seasons above combined. The second row shows the four players in the chart above with their combined stats from 2011 to -15. Arrendondo did not play after 2012 and Putnam did not play much before 2014, so it is basically adds in a few extra seasons of Uehara and Mujica.

It’s clear that the splitter pitchers are better than the rest of the relief population. By strikeouts, walks, ERA, and FIP, the pitchers who utilize the splitter are better than your average reliever. What appears interesting is that the pitchers, despite being above-average overall, were not above-average in terms of home runs per nine innings and home runs per fly ball. Looking at reliever leaderboards over the past five seasons, one finds 18 relievers who’ve produced at least five wins and Uehara is the only one with a HR/9 over 1.0 during that time.

Whether there is something to the homer tendencies of pitchers with high splitter usage likely requires further study, but Neris has had some issues with the long ball in the past, giving up 10 home runs over 57.1 innings since the beginning of last season with a HR/FB rate near 15%. Neris is having tremendous success using the splitter a ton, and he is not the first pitcher to do so. It’s possible that he could continue to beat his FIP with perhaps a few more home runs than the average reliever. Given his success compared with his history, there is definitely no reason for him to stop.