Some key adjustments have unlocked a new level of performance in 2021. Is this success sustainable?
Many pitchers making their debut on a major league mound find the leap from lower levels of professional baseball to be a large one. Willians Astudillo is no exception. When he toed the rubber at Target Field for the first time against the Tampa Bay Rays in July of 2018, he almost certainly was not expecting what came next. The first batter Astudillo faced, former Twin Carlos Gomez, hit a nearly 400 foot home run. The next hitter doubled. The one after that singled.
By the time Astudillo managed to coax three outs to escape the inning, he had given up five earned runs on five hits, three of which went for extra bases (including another 400 foot homer). He left his first major league outing with an ERA of 45.00. After that disastrous debut, the Twins would not entrust him with another mound opportunity for the remainder of the 2018 season. They passed over him for all of 2019 and 2020, as well.
Baseball has a way of giving second chances, though. After a long wait, Astudillo was given the ball once again in April of 2021 in Anaheim. This time, a more experienced Astudillo set down three Angels in order. With the confidence boost of that outing behind him, Twins Manager Rocco Baldelli has continued to give Astudillo opportunities on the bump this season. And he has delivered. Altogether, he has worked to a 2.25 ERA and 0.75 WHIP.
On a Twins pitching staff that has struggled this season (5.00 ERA, 27th in MLB), Astudillo’s numbers stand out:
Willians Astudillo has a lower ERA than 27 of the 31 actual pitchers who’ve appeared in a game for the #MNTwins this season.
— Aaron Gleeman (@AaronGleeman) August 27, 2021
Given his performance this season, I got curious about what he has changed from his first opportunity back in 2018. Pitchers can unlock new levels of performance with a new pitch or a new approach in how they use their pitches. What does the data reveal about the new Astudillo?
It turns out it’s a combination of both a new pitch and a new approach that is driving his strong season.
Against Tampa Bay in 2018, Astudillo fell into a trap that many inexperienced hurlers get caught in — relying too heavily on his fastball. Experienced veteran pitchers often do a better job than rookies of mixing their pitches to keep batters off balance. That day, Astudillo’s inexperience led him to throw his fastball thirty-four times out of his thirty-five total pitches (97%).
Not only was he too predictable, but he also struggled with his command in that outing. He left far too many of those fastballs up and in the middle of the plate, as this heat map of his pitch locations from that day shows:
Beyond the lack of variety and poor location, Astudillo also kept stubbornly offering the Rays hitters his fastball despite it’s very hittable velocity. He averaged 82.9 miles per hour on his heater that day and topped out at 86.2.
This total combination allowed batters to have comfortable at-bats and look for pitches in the heart of the zone that they could drive. The net result was all those extra base hits I mentioned above and an average exit velocity allowed of 93.8 mph off the bat. In fact, two of the three hardest hit balls in that entire game were allowed by Astudillo.
This season, it’s become obvious that Astudillo has learned some lessons from his past failure. He has altered his pitch mix to feature offspeed pitches much more prominently and worked to slow down the velocity of his fastball far below normal hitting speeds (living up to his La Tortuga nickname).
We most often hear about pitchers doing everything they can to maximize their fastball velocity because faster fastballs are harder to hit. But pitching is a relative endeavor and pitchers have more options at their disposal than just going faster. Deviating from what batters are used to or expecting is the key. In that sense, slowing down can also be an effective strategy.
Now, Astudillo is averaging a more uncommon 75.0 mph on his fastball and throwing it only about one out of every four pitches (23.5%). He’s also reduced the pitch’s spin rate about 130 RPMs on average, giving it better sinking movement than before. The remainder of his arsenal is made up of a variety of offspeed pitches that get classified in the Statcast pitch tracking system as “eephus pitches” that more or less look like this:
Willians Astudillo, Sinister 41mph Eephus. pic.twitter.com/ZPWx6oTQbq
— Rob Friedman (@PitchingNinja) June 5, 2021
These change of pace offerings have averaged 45.2 mph, giving Astudillo one of baseball’s largest velocity differentials between fastballs and offspeed pitches. As a result, he can weaponize how those pitch types pair together to yo-yo hitters back and forth within an at-bat, as this pitch overlay illustrates:
Willians Astudillo, 72mph Fastball and 46mph Slowball, Overlay. pic.twitter.com/xE9LxNbRqF
— Rob Friedman (@PitchingNinja) April 17, 2021
Not only is Astudillo offering different looks to hitters, he’s also able to locate those eephus varieties in much more favorable locations in and around the strike zone. Instead of working in the heart of the plate with fastballs as before, he’s now around the edges:
With these combinations of adjustments in place, Astudillo has turned his pitching career around after its disastrous start. His success is supported by some of the key below the surface stats, as well. He has held opposing hitters to .071 batting average, .188 on base percentage, and .286 slugging percentage, thanks in large part to a 57.1% ground ball rate. Those are outstanding marks.
Of the 763 players to have faced at least ten plate appearances from the mound this season, Astudillo’s .071 opponent batting average allowed is second-best. His .188 opponent on base percentage allowed is 6th-best, right behind Jacob deGrom (.160). While those actual numbers are outperforming his Statcast derived expected stats, his xBA, xOBP, and xSLG marks are still a respectable .219/.316/.442.
Now, all that’s left is to find out if Astudillo’s new approach has staying power. Is this kind of success sustainable? Can he continue to be successful after the league has seen him a few times?
We can turn to the run prevention estimators for some clue on those questions. We rely on these kinds of data-driven models to evaluate how much luck is at play in a pitcher’s performance.
Unfortunately, they don’t look very kindly on Astudillo’s work thus far.
Astudillo’s fielding independent pitching (FIP) mark is 7.92, about three times more than his actual ERA. Statcast’s expected ERA (xERA) sees his work a little more favorably at 4.89, but that’s still more than twice his current ERA.
These large discrepancies are largely because the models don’t think Astudillo’s .000 batting average on balls in play (BABIP) is sustainable. Given that the league average is .289, they might be right. The models also don’t like Astudillo’s 0.0% strikeout rate (league average 23.4%) or 12.5% walk rate (league average 8.7%). In his favor, though, is that his home runs allowed per fly ball rate is 25%, about double the league average of 13.6%. This suggests he might experience some better fly ball fortune going forward.
If you roll it all up, it’s a package that probably is not sustainable at these high levels in the long term. He’s likely to experience regression in the batted ball luck department and without finding a new ability to get some more strikeouts to counter those base hits will struggle to remain a 2.25 ERA kind of pitcher.
Nonetheless, Astudillo has never been a pitcher that relies on the advanced analytics that are a prominent factor in how the game is played today. Instead, he’s more of a grinding, guts and guile type who succeeds more with an infectious and determined attitude than data. With the success he’s had, especially relative to some of his bullpen counterparts, it’s easy to wonder if Baldelli will start to look Astudillo’s way in higher leverage situations (Editor’s note: Just Stop.)
In any event, count him out at your own peril. After all, the zig instead of zag adjustments he’s implemented this season have worked out. That might suggest he can continue to find ways to keep hitters off balance going forward.
John is a staff writer for Twinkie Town with an emphasis on analysis. He is a lifelong Twins fan and former college pitcher. You can follow him on Twitter @JohnFoley_21.