How good can Zach Eflin be?
It’s come to my attention that an increasing number of Phillies fans are writing off Zach Eflin. It doesn’t take too much time on Phillies Twitter to see fans labeling Eflin a number 4 or 5 starter, claiming he’s terrible, and clamoring for another arm for the rotation.
I would argue that it’s far too early to have your mind made up on a pitcher like Eflin. He’s only 26 years old and this is just his third year as a full-time starter in the Phillies’ rotation. Not to mention that this is his first year under a new coaching staff, one that is finally letting Eflin be himself.
The Phillies acquired the former first-round pick from the Dodgers in December 2014 in exchange for Jimmy Rollins and was soon regarded as a top-five prospect in the Phillies’ system.
Eflin exhausted his rookie status in 2016 when he threw 63.1 innings. He tossed 64.1 innings the following season, but he bounced back and forth between Lehigh Valley and Philadelphia both years. It wasn’t until 2018 that Eflin earned a full-time spot in the rotation. It just so happened to be the first season under manager Gabe Kapler and pitching coach Chris Young.
Young’s philosophy centered around challenging opposing hitters with high fastballs, even if that wasn’t a player’s forte. Eflin has poor fastball spin and his velocity on his four-seamer is middle-of-the-pack, so relying heavily on a below-average pitch didn’t yield strong results.
Eflin is a sinker ball pitcher. The report on Eflin had always been that, despite his five-pitch arsenal (he ditched the cutter that he started throwing last season), he didn’t have another plus pitch to turn to when he needed to put a hitter away. That’s why his strikeout rate has been so low since he came up in 2016.
Under this new coaching staff, manager Joe Girardi and pitching coach Bryan Price have completely renovated Zach Eflin — letting him be the pitcher he wants to be — and the Phillies might just have a future ace on its hands because of it.
Below is Eflin’s Statcast profile for the 2020 season. It’s really good.
EFLIN IS A DIFFERENT PITCHER NOW
Over the past two seasons, Eflin was a fastball/slider pitcher who worked his sinker into the mix somewhat sparingly. This season, Eflin has hardly thrown his fastball, doubled the rate at which he throws his curveball and relying less on the slider and much, much more on his sinker.
Eflin is throwing his sinker over half of the time, as he should be. His sinker is really good. There are 33 pitchers who have thrown at least 200 sinkers this year. Of those 33, Eflin’s sinker has the fourth-best expected weighted on-base average (xwOBA), the ninth-best expected slugging percentage (xSLG), and the second-best expected batting average (xBA). He also ranks 12th among that group in average velocity on his sinker (93.7 mph).
His sinker moves pretty well, too. This season, Eflin’s sinker is dropping 23.2 inches, which is 11 percent more drop than average. It’s also breaking 16.6 inches horizontally — 16 percent more break than average.
Another thing worth noting: Eflin has much better command and control of his sinker than he does his fastball.
Eflin has thrown his sinker for a ball just 30.8 percent of the time since 2019 — the ninth best rate among 52 pitchers who have thrown at least 400 sinkers since then. He’s thrown his fastball for a ball 34.2 percent of the time, which puts him 86th out of 144 pitchers who have thrown at least 750 fastballs since last season. Increasing his sinker usage has allowed Eflin to work ahead more often and finally put another plus pitch to use: his curveball.
Eflin’s curveball this season has been spectacular and is a huge reason why his strikeout rate has jumped 11.7 percent since last season and sits in the 82nd percentile among MLB pitchers in 2020.
Of the pitchers who have generated at least 25 swings on their curveball this season, Eflin has a higher rate of swings and misses (36.0 percent) than guys like Clayton Kershaw, Jack Flaherty, Mike Clevinger, Dustin May, Kyle Hendricks and Lance Lynn.
When hitters are making contact with his curveball, they aren’t getting very good wood on it. Of the 127 pitchers who have thrown at least 50 curveballs this season, only one pitcher has a better expected weighted on-base average (xwOBA) on his curveball than Eflin. Batters just aren’t hitting his curveball.
- Corbin Burnes — 0.044
- ZACH EFLIN — 0.072
- Adbert Alzolay — 0.094
- Evan Marshall — 0.115
- Lance Lynn — 0.127
If you look at the 137 pitchers who have had at least 15 plate appearances decided on a curveball this year and order them by lowest weighted on-base average (wOBA), Eflin is in the top ten.
Eflin is also striking out a ton of hitters. As of today, Eflin has struck out 30 percent of the batters he’s faced this year, despite not generating a lot of swings and misses. He has excellent command of his sinker, but he also pitches it to contact, thus resulting in a high rate of called strikes and foul balls. Only three pitchers this season with at least 400 pitches have had a higher rate of pitches that were called strikes or fouled off.
He’s getting ahead in the count and then putting batters away with his sinker and his curveball.
Eflin’s huge leap in strikeout rate should be encouraging. It would be nice to see him maintain this rate throughout the rest of the season and the playoffs, since this season isn’t a real season — it’s a small-sample-size season. Nonetheless, Eflin has never pitched like this before — the pitches he’s utilizing, working ahead in the count, striking out a high rate of batters, and walking fewer batters. It’s OK to believe that this is the new Zach Eflin.
The two best things a pitcher can do are strike out a lot of batters and limit hard contact. Eflin has been exceptional at both this year.
Eflin currently boasts a 77th percentile hard hit rate and a 76th percentile average exit velocity. When he’s not striking batters out, he’s forcing them into weak contact. However, when he does get hit hard — he gets hit hard, as his barrel rate is down in the 34th percentile.
Of the 33 pitchers who have thrown at least 200 sinkers this season, Eflin has produced the fourth-highest rate of weak contact (balls hit with an exit velocity of 80 mph or lower) on his sinker. That’s exactly what you want out of a pitcher: weak contact.
THE PROBLEM WITH ERA
The one thing most fans use to judge a pitcher is ERA, which is what we were all taught to look at when first learning baseball. It makes sense; the name of the game for a pitcher is run prevention, so ERA can give us an easy-to-understand number that reflects how good a pitcher has been at preventing runs. However, ERA has some serious flaws; it is not a sound measure of a pitcher’s true talent or performance.
Eflin’s ERA isn’t great this year, but it is by no means horrible, as many fans try to make it out to be. Eflin’s 4.51 ERA is right around league average (4.49), but his 3.30 expected ERA (xERA) is in the 90th percentile. You can read more about expected ERA here.
ERA does a poor job at differentiating between runs that were the pitcher’s fault and runs that weren’t. Earned runs and unearned runs are determined by human discretion; the scorekeeper rules whether or not a play was an error. We know this is not always accurate nor is it always consistent.
Earned runs — which ERA would suggest is always the pitchers fault — does not take into account bad defense. A team can have poor defense without committing tons of errors, thus inflating its pitchers’ ERAs.
What if there’s a slow ground ball to the shortstop and he falls down as he’s charging it? That’s not an error, so if that runner comes across to score, it is considered an earned run and is reflected in that pitcher’s ERA.
What if a team has poor outfielders and there’s a flyball that one of them gets a horrible jump on and takes a really bad route to track it down? The ball finds the grass and the runner is on second or third, but an above average or average outfielder likely would have made the catch. That’s not the pitcher’s fault.
With all of the science, tracking, and data we have today, there are statistics that explain what ERA is trying to accomplish and do a much better job of it. These stats strip a pitcher’s defense out of the equation and take into consideration other factors that are out of the pitcher’s control, while putting more weight on factors that are within a pitcher’s control.
Evaluating pitching is not as easy as looking at his ERA and saying, “Zach Eflin has a 4.51 ERA, he must stink.” That’s basic, surface-level thinking. Some of these stats can be confusing at first. They’re new to a lot of people, but just because you don’t understand what these stats are telling you does not make them any less valid or any less impactful. I encourage you to be open-minded.
This information is all there to be used to gain an advantage, whether that’s as a fan in how you watch and understand the game or as an executive in finding a hidden gem in a back-of-the-rotation arm, getting a steal on a strong reliever in free agency, or buying low at the trade deadline on a player with good expected statistics. Analytics are not the end-all-be-all, but they are another piece of the puzzle in player evaluation and performance.
STAT TALK
One of the metrics we can look at with Eflin is his Fielding Independent Pitching (FIP). This metric measures what a pitcher’s ERA would look like over a given period of time if he were to experience league average defense and timing.
Eflin’s 3.75 FIP is 38th among 97 starters with at least 30 innings pitched this season, ahead of Jose Berrios, Carlos Carrasco, Lance Lynn, and Patrick Corbin.
We can take this metric one step further to get another useful measurement for evaluating Eflin’s true performance this season: Expected Fielding Independent Pitching (xFIP).
Expected Fielding Independent Pitching is a regressed version of Fielding Independent Pitching. xFIP estimates a pitcher’s expected run prevention independent of how his defense performs, so it’s based on outcomes that don’t involve defense: strikeouts, walks, hit by pitches, and fly balls allowed.
FIP tells you how a pitcher has performed (value) independent of their defense while xFIP tells you about how well he has pitched (ability, talent) independent of their defense. xFIP is a great way to tell how well a pitcher has been throwing the ball. — FanGraphs Library
Eflin’s 3.20 xFIP is fantastic (4.42 is the league average this year), and good for 16th among the 97 starters with at least 30 innings pitched, ahead of Max Scherzer, Gerrit Cole, Zack Wheeler, and Max Fried.
Another metric that really loves Eflin is Skill-Interactive ERA (SIERA). I won’t bore you with more stat talk, but I encourage you to read FanGraphs’ page explaining all about SIERA and how it’s more predictive than FIP and xFIP and how it just might be the best way to measure how good a pitcher truly is.
Zach Eflin’s 3.36 SIERA this season is really, really good. Like, 14th-best-in-the-MLB good.
Again, here is Fangraphs’ SIERA rating scale and how it should be interpreted.
Eflin’s .291 expected weighted on-base average (xwOBA) is elite, as well — placing him in the 89th percentile among all regular starters this season. It simply shows how well he’s pitched — striking out tons of batters, walking very few and generating weak contact. His ERA will start to reflect his true performance soon.
EFLIN’S CEILING
When you dig a little deeper and look at stats that give us a better indicator of how well Eflin has been pitching this year, it’s difficult not to get excited about what he could turn into. Whether you believe in him or not, he is absolutely trending in the right direction.
Eflin has pitched really well this year, and with more time to blossom under this coaching staff, I don’t think it’s unreasonable to expect continued improvement, which means we need to adjust his ceiling accordingly.
People get so worked up over ceilings and floors. When I explain Eflin’s ceiling, it is in no way what I think he is right now. It’s simply what I believe to be the best possible outcome among his range of outcomes, with his floor being his worst possible outcome.
With how he’s looked this year, I think it’s absolutely fair to say Eflin’s new ceiling is a high-end number two starter (maybe a fringe ace) with a floor of a low-end number three starter. Will Eflin ever reach that ceiling? He may not, but as of right now, he’s on the right path. If he doesn’t reach that ceiling, he is certainly a pitcher I would pay to keep around to bolster the middle/back-end of therotation. If he does reach that ceiling. Aaron Nola, Zack Wheeler and Zach Eflin are a terrifyingly good trio.
Don’t give up on Zach Eflin just yet. He might surprise you.
