Peter Majors
Photo courtesy of Marcio Jose Sanchez of AP Photo
One of the biggest challenges for professional athletes who play for smaller market teams, particularly those on the West Coast, is that they are difficult to market - or that they are at least more difficult to market than their east coast counterparts. This is in large part due to the fact that West Coast teams play their games later at night - meaning that they don’t get as much viewership on the east coast, where nearly half of all Americans live. This is an issue that Major League Baseball is not immune from.
Current notable underrated players on the west coast include Oakland Athletics defensive wizard Matt Chapman, Colorado Rockies slugging shortstop Trevor Story, and Los Angeles Angels speedy second basemen David Fletcher. Despite their incredible production at the plate and in the field, these players seem to get overlooked by casual fans.
In this piece, I will argue that another player needs to be added to this unofficial list of West Coast should-be superstars. That player is none other than Zac Gallen: starting pitcher for the Arizona Diamondbacks.
Gallen was drafted in the third round of the 2016 Major League Baseball Draft by the St. Louis Cardinals. That offseason, he was traded to the Miami Marlins in a package that sent slugger Marcell Ozuna to the Cardinals. During the 2019 trade deadline, Gallen was sent to the Diamondbacks for then top-prospect, and now starting second-baseman for the Marlins, Jazz Chisholm. Since being traded to Arizona, Gallen has proven himself to be a reliable starting pitcher, capable of going deep into games.
Since making his debut in June of 2019, the right hander has sported the ninth best ERA among all qualified starting pitchers in Major League Baseball. Through eleven starts this season, Gallen has posted a 3.00 ERA, a 1.11 WHIP, and has held opposing batters to a .207 BA. For the more advanced readers, Gallen has posted a 66 ERA-, a 88 FIP-, and has held opposing batters to a .273 wOBA.
So, you may be asking, "What makes this Zac Gallen guy so darn good?” or “Why should I care about this obscure starting pitcher on the Diamondbacks?”. Well, I’ll tell you why.
Despite throwing just about a league average fastball in terms of velocity, Gallen's primary pitch possesses some great spin rate - averaging 2383 rpm. When paired with its average velocity of 93.2 mph, that comes out to 25.57 Bauer Units – which is roughly 1.5 units greater than the major league average. This is one of the reasons why the pitch drops 1.4” less than the league average fastball. That might not sound like much, but when dealing with pitches that reach the plate in literal fractions of a second, that can mean the difference between a swing and miss and a homerun.
Opposing batters have managed a measly .169 BA and .243 wOBA against Gallen's fastball this season. However, that pitch alone is not the reason for his success. In order to understand why Zac Gallen has been so good, we need to examine the rest of his repertoire.
Let us begin by taking a look at the pitch he throws next to as often as his fastball: his cutter. Looking at traditional and advanced metrics, Gallen's cutter profiles as being well below league average in terms of batter outcomes. This season, opponents are hitting .306 against Gallen's fastball variant with a .352 wOBA in 2020 – both of which are the worst of any pitch he throws.
Despite this, Gallen has dramatically increased his usage of the pitch in 2020,
up to 26% this season from 15.4% in 2019. So, if the pitch is not especially effective, then why the increase in usage?
According to Baseball Savant's Pitch Movement Leaderboard, Zac Gallen has the fourth best cutter in the league in terms of horizontal break. On average, it moves a whopping 6.5 inches, which is more than twice the major league average for that pitch.
As you can see, the above pitch looks much more like a traditional slider than a cutter - and without the above caption, I could have easily been fooled myself. In fact, Gallen's cutter possesses a set of Movement Traits which make it nearly identical to that of the average major league slider. Gallen's cutter on average breaks 6.5" horizontally and 32.6" vertically. Meanwhile, the average major league slider breaks 5.7" horizontally and 36.9" vertically.
Gallen's fastball variant is also unique in that he throws it fairly hard – after accounting for its incredible break. He throws his cutter at an average of 87.1 mph which is just about the same as the league average cutter velocity and 3 mph faster than the league average slider velocity.
Thus, Gallen is effectively throwing a mix between a slider and a cutter. The pitch possesses the velocity of a typical cutter and the movement profile of a typical slider – allowing him to utilize the best characteristics of each pitch type. Despite this, Gallen’s sweeping cutter has performed quite poorly for him in terms of batter outcomes up to this point in his career. However, if we look at Gallen’s sweeping cutter instead from the perspective of how batters are interacting with the pitch, we see a vastly different story.
In 2020, the Hard-Hit Percentage on Gallen’s fastball and cutter have both fallen dramatically from last season. They are down 12.8% and 15.2%, respectively. Also, last season both pitches had a Hard-Hit Rate of above 40%. However, this year they are only being hit hard 28% and 26.1% of the time - which is well below the league average of 37.4%. Furthermore, the Average Exit Velocity on Gallen’s cutter has decreased from 87.7 mph last season to 83.7 mph this season.
These indicate that batters are not hitting Gallen’s cutter hard, and when they are hitting it hard, they are doing so infrequently. One reason behind this may be that Gallen has adjusted the usage of his fastball and cutter this season.
In 2020, Gallen has decreased his fastball usage from 47.6% to 38.3% and increased his cutter usage from 15.9% to 26%. Since he has not significantly changed the usage of his curveball or changeup from last season, this represents a roughly 10% swap in the usage of these two pitches from last season. Intuitively, it would make sense that a decrease in fastball usage and an increase in cutter usage would yield worse results for each – since hitters are then less able to sit on either pitch.
Going forward, this rebalancing of Gallen’s fastball and cutter usage will serve him well. The early returns in terms of batter interactions are encouraging, so logically better batter outcomes ought to follow. In short, Gallen’s cutter is not as bad of a pitch as its batter outcomes would suggest – and with a greater sample size, should reveal itself to be a legitimate weapon in Gallen’s arsenal.
Now, let’s take a look at Gallen's curveball - a pitch which has become the most effective in his repertoire in terms of batter outcomes. So far this year, Gallen's curveball has yielded a .103 BA, a .131 wOBA, and a 36.1 Whiff%.
Unlike his cutter, not much has changed in terms of how Gallen has been employing his curveball this season. In each of the last two seasons, he has thrown it between 16% and 19% of the time. The pitch is about league average in terms of spin rate, movement, and velocity. However, it has been nothing short of magnificent for the right hander this season.
The only way in which Gallen’s curveball has been different from last season is that it now possesses 3” less of vertical break. This means it has taken on a more 12-6 shape, allowing it to be tunneled much more effectively with his fastball. For an example of this, see the overlay below.
As you can see, the late break on Gallen's curveball makes it extremely difficult to hit, especially when it is thrown following a fastball. The above pitch looks as if it is a belt-high fastball until the very last second, which is when it completely drops off the table.
The fourth and final pitch in Gallen's arsenal is his changeup. He throws the pitch 18% of the time and almost exclusively to left-handed batters - employing it about 85% of the time against them. As one would expect, this is when it has seen its most success.
Against left-handed batters this season, Gallen's changeup has yielded an exceptional .276 wOBA, while against right-handed batters, it has yielded a horrid .592 wOBA. If you prefer more traditional metrics, left-handed batters are hitting .216 and right-handed batters are hitting .333 against the pitch this season. Either way you slice at it, the pitch has been much, much better against left-handed batters.
Looking solely at the makeup of the pitch, Gallen's changeup possesses 2.9 inches, or 9%, more vertical break than the league average changeup. Below is a collection of changeups Gallen threw in a start earlier this season against the Oakland Athletics.
Much like the other pitches featured in this article, Gallen's changeup is indeed nasty. As you can see, Gallen is able to produce great depth on his changeup. It is because of this depth that the pitch has generated an excellent 44.7 Chase%, 44.1 Whiff%, and 29.2 PutAway%. All of these are the highest of any pitch in his repertoire.
Looking again at batter outcomes, Gallen's changeup has yielded a .211 ISO this season - meaning that the pitch is being hit for extra bases at a rate far higher than league average.
Thus, Gallen's changeup is great on paper and in practice. It generates swings and misses, puts hitters away, and is a nightmare for left-handed batters. However, from time to time, Gallen will hang one - and batters, right-handed ones especially, will take advantage. No one pitch is perfect, but Gallen's changeup is pretty darn good.
So, let’s summarize. Since his arrival, Zac Gallen has indisputably been one of the top dozen or so starting pitchers in all of Major League Baseball. Both the traditional and advanced metrics agree that he is deserving of the success he has seen. However, he receives little recognition because he plays on a small market team that, at least recently, has been out of postseason contention.
He throws four pitches that are each special in their own way: a seemingly average fastball that possesses above-average spin rate, a hard-sweeping cutter which ranks among the league's very best in terms of horizontal movement, an average curveball in terms of velocity and break which he has learned to command and sequence effectively, and a changeup with great depth that allows him to put hitters away. Gallen is able to throw both his cutter and his curveball off of his fastball – creating two vastly different pitch pairings to keep hitters off balance. He can also mix things up every once and a while against left-handed batters with the help of his changeup.
Zac Gallen is not the most physically imposing pitcher you have ever seen, nor does he have an incredibly deceptive motion – but what he lacks in those departments he more than makes up for in terms of stuff. The sky is the limit for Gallen, and I am excited to see how he continues to develop as a pitcher.
So keep an eye on Gallen - because he is just one of many players on small-market, West Coast teams who deserve far more attention than they are being given.
Sources
@pitchingninja on Twitter
Marcio Jose Sanchez of AP Photo