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# Let's watch Trevor Bauer employ effective velocity

The most notable pitcher committed to an effective velocity based approach, let's examine the specifics of a few of his recent sequences through the lens of effective velocity.

"Hitting is timing, pitching is upsetting timing." – Warren Spahn

Pitch sequencing, at its most basic form, is the art of mixing one’s pitches and locations effectively so that the batter never knows what pitch is coming and where it will be thrown. This art has been subject to many theories over the years, which contain hitter-dependent approaches (i.e. throwing to a batter’s weak spot), pitcher-dependent approaches (throw your best stuff regardless of the hitter), and various combinations of the two extremes. Regardless of the approach, however, one consistent aspect of this part of the game is that pitch sequencing has long been considered an art…until recently.

Perry Husband uses the name "effective velocity" (EV) for his pitch sequencing theory, which is explained brilliantly in this long-form piece by Jason Turbow. Jason's piece is well worth a read in full, but for the purposes of this article I’ll pull out a few highlights for a brief explanation of the foundation for the theory of effective velocity.

Husband's model is based on the arc of hitters' swings, and the understanding that bats must move farther to reach pitches on the inner part of the plate than on the outside edge. Put another way, a batter can hit an outside fastball as it crosses the plate, but to make solid contact with an inside fastball, he must reach it much sooner — up to 2 feet in front of the plate — which requires the hitter to move the bat a greater distance in less time. With this detail in mind, it makes sense to build an approach based not on a pitch's radar speed, but how quickly the man standing in the batter's box can react to it.

Turbow goes further into explaining the specific effect that effective velocity has on a hitter’s timing as well as the zero line, which is the basis for all EV-adjustment calculations.

There is an imaginary stripe that runs diagonally across the strike zone, from the batter's feet to shoulder level in the opposite batter's box, where a pitch's EV equals its actual speed. Husband calls this the Zero Line. He calculated that for every 6 inches the ball moves closer to the hitter from that line, it picks up 2.75 EV mph; for every 6 inches it moves away, it loses an equivalent amount. This gives strikes thrown at identical speeds on a given horizontal plane about a 6-mph fluctuation in reactionary speed from one end of the strike zone to the other. Add vertical differences into the equation and that spread can easily double, all for pitches that are thrown at the same actual speed.

According to Husband’s findings, a 90 MPH pitch in the strike zone can have an EV of anywhere between 96 MPH if located up and in, and 84 MPH if located down and away. If the theory holds, this is a major breakthrough that completely redefines the art of ideal pitch sequencing. Instead of basing sequencing on "feel" or a hitter’s tendencies, an EV-based approach is a mathematically based approach fundamentally aimed at upsetting a hitter’s timing by using the principles of EV to one's advantage. There is still an art to executing an EV-based game plan, but the math-based theory of EV makes the art less of a guessing game and more of a calculating chess match.

Put in graphic form, the approximate strike zone adjustments in velocity added or lost are shown in the chart below. The chart is shown for a left-handed hitter from the catcher's perspective. So the top-right is up and in, and bottom-left is down and away. Note that these regions are approximations and pitches in different parts of a region could have slightly different actual EV’s, specifically that pitches closer to the "Zero Line" will be less affected by EV while those farther away from the line will be more affected. Additionally, since the PITCHf/x zones are slightly less than six inches (5.66 to be exact), I adjusted EV for each zone accordingly (hence the 2.6 MPH adjustments instead of Husband’s 2.75). The numbers in parenthesis are zone location numbers for each individual region, which will be helpful in understanding charts later in this article.

Cleveland Indians’ righthander Trevor Bauer is the most notable pitcher in the Major Leagues who subscribes (at least openly) to Husband’s theory and applies it during his outings. Bauer is also a great pitcher to examine because he uses a multitude of pitches, including one, the reverse slider, which is not even categorized by the PITCHf/x pitch types. It is fun to look at Bauer’s pitch breakdowns at sites such as Brooks Baseball or Baseball Savant, but the essence of EV is sequencing within an at-bat so that the pitches have a chance to play off of each other with respect to EV.

With that in mind, let’s take a look at one example of Bauer employing the concept against a specific hitter this season. There is nothing special about this Trevor Bauer versus Eric Hosmer matchup on September 24 apart from Bauer throwing at least three pitches to Hosmer in each plate appearance and the relative recency of the game. Other than that the selection of this matchup was arbitrary.

For each of Hosmer’s plate appearances against Bauer in this game, I will show the pitches in graphical form (courtesy of Brooks Baseball) and in chart form using PITCHf/x data. In the chart, I will include a zone location in the form of a number between zero and 24. These zone locations are listed in parenthesis in the chart above and as mentioned are from the catcher's perspective, meaning that zone four is up and in to the lefthanded hitting Hosmer and zone 20 is low and away. Also, all pitch classifications are according to those given at Brooks Baseball.

#### Plate Appearance One

Pitch # Result Pitch Type Velocity Zone Location EV Adj EV
1 Foul FF 93.0 13 2.6 95.6
2 Called Strike CH 83.8 16 -5.2 78.6
3 Ball CU 78.4 24 0 78.4
4 Ball FF 94.6 4 10.4 105.0
5 In play, out(s) CU 77.7 14 5.2 82.9

Hosmer was the first batter of the second inning, and Bauer started him with a fastball inside registering a 95.6 EV. Hosmer pulled it foul, letting Bauer know that the hitter’s timing was close to or even slightly above mid-90’s velocity. With the next pitch, conventional EV theory suggests that the pitcher should throw anything but a pitch with a mid-90’s EV. Bauer obliged, throwing a changeup down and away with an EV of 78.6. Hosmer wanted no part of the 17 MPH difference, letting the pitch go for a called strike two.

Bauer had no reason to believe that Hosmer’s timing had changed, so he tried another pitch with a low EV. This time he went to the curveball, which missed down and in for ball one. One will note that this pitch was on the zero line, where pitches see no EV-adjustment, but throwing on the zero line isn’t inherently bad. EV goes well beyond the concepts of hard in and soft away, especially when the hitter is timed to a pitch significantly faster than the traditional velocity of the pitch.

Presumably thinking that Hosmer was catching on and wanting to maintain timing to high velocities so it could be easily exploited, Bauer showed Hosmer another fastball up and in. This time he increased both the velocity and EV of the pitch, the latter of which ran all the way up to 105.0. That’s much faster than the prior heater that Hosmer lined foul and was also thrown to a spot where it is virtually unhittable. This was purely a show-me pitch, thrown with the hope that Hosmer might chase, reminding him that he had to be ready for the high heat and most importantly, setting him up for another offspeed pitch.

Bauer went back to his offspeed stuff with the next pitch, throwing a curveball on the inner half that Hosmer grounded back to Bauer for an easy out. The pitch actually gained EV, but an 82.9 EV was still more than enough of a difference from Hosmer’s timing that Bauer was able to retire him just by throwing the pitch near the strike zone.

#### Plate Appearance Two

Pitch # Result Pitch Type Velocity Zone Location EV Adj EV
1 Called Strike CH 85.2 17 -2.6 82.6
2 Ball FF 94.9 24 0 94.9
3 In play, out(s) FF 94.2 3 7.8 102.0

Following a successful bunt hit by Lorenzo Cain to lead off the fourth, Bauer began his second plate battle with Hosmer by throwing a changeup with an 82.6 EV down in the zone for a called strike one. The next pitch was a bit more curious. Perhaps it was the threat of Cain running or perhaps Bauer thought Hosmer had made an adjustment to his barrage of offspeed pitches in his first plate appearance, but either way he missed down and in with a fastball. This is odd, as Bauer almost always throws his four seamer up in the zone, but the target was down and in so it seems to have been intentional. Perhaps he was aiming to throw the pitch above the target, but it ended as a wasted pitch.

The 1-1 offering from Bauer was another four-seamer, this time up and in with an EV of 102 MPH. The added effective velocity was enough to beat Hosmer again, who grounded the ball weakly to first base for another easy out.

#### Plate Appearance Three

Pitch # Result Pitch Type Velocity Zone Location EV Adj EV
1 Ball CH 83.2 0 0 83.2
2 Swinging Strike (Blocked) CH 85.0 23 -2.6 82.4
3 Ball FC 88.8 24 0 88.8
4 Foul CH 84.5 21 -7.8 76.7
5 Ball CU 80.7 23 -2.6 78.1
6 Foul CU 79.3 12 0 79.3
7 In play, run(s) FF 97.2 12 0 97.2

With two runners on base and one away in the fifth, Hosmer stepped to the plate for a third time. Bauer shook to a changeup down and away on the first pitch, but missed his spot and left it up and away out of the zone. Following the wasted pitch and not wanting to give in, Bauer came back with a better changeup, this time with an EV of 82.4 for a swinging strike one. Hosmer looked bad on the pitch, so Bauer went back to a similar spot, albeit with a different pitch. His third pitch was a cutter, a pitch that Hosmer hadn’t seen yet, but Bauer buried the pitch for ball two. This offering had a bit more movement than a traditional cutter and one could argue that it was a slider, but either way it had an EV of 88.8, slightly higher than the previous offerings.

The 2-1 offering was another changeup, this time down and away, that had a velocity of 84.5 but lost 7.8 MPH due to the location, giving it an EV of just 76.7. The huge velocity difference had Hosmer well out in front, and he pulled it foul on the ground for strike two. Seeing that Hosmer was so far ahead of the mid-70’s EV, Bauer went back to another pitch with a similar EV for his next offering, a curveball down with an EV of 78.1. The pitch was very tempting for Hosmer and he wouldn’t have been able to do any damage with it had he swung, but an appeal confirmed that he successfully checked his swing.

The count ran full, and not wanting to load the bases, Bauer had to throw Hosmer a strike. Still confident in his offspeed stuff, Bauer went back to the curveball, which broke down the middle of the plate on the zero line, maintaining its actual velocity of 79.3, but was fouled back. This was the first time that Hosmer showed the ability to adjust to pitches with a low EV, making it a good time for Bauer to try to beat him with something else. 79.3 is close to the lower end of Bauer’s EV range, so to change the speed most drastically, a fastball and/or something up and in would be the best selections.

Bauer decided on the fastball, which was targeted away but left over the middle of the plate. His objective with this pitch is a little bit unclear, as catcher Yan Gomes set up down and away and motioned that he wanted the pitch down, but Bauer is known to have an aversion to throwing fastballs low in the zone. So, perhaps Bauer wasn’t aiming at the glove and instead at the top of the zone, but either way Hosmer was all over the 97.2 MPH heater on the zero line and lined it up the middle for a single. If the pitch was a bit higher, it is conceivable that the additional EV would have been enough to miss Hosmer’s bat and result in a swinging strike three. But with a full count and two runners aboard, it was difficult to risk walking Hosmer on a pitch up and out of the zone.

#### Final Thoughts

This is one small sample from one game, but it is conceivable that these are the types of analyses going on in Bauer’s head during the game. I can’t claim that Bauer’s reasoning for his pitch selection in this sample is the same as the reasons I offered above, but, at the very least, this should give the reader a practical idea of an in-game, EV-based approach. Each pitcher will have a different idea of how to approach hitters from an EV perspective, but the one constant is taking the EV adjustment into consideration. The theory of EV doesn’t tell one how to pitch and is much more than hard up and in, soft low and away; instead it gives the pitcher a more thorough understanding of how to use different speeds and locations to their advantage. There are many ways to do this, as Bauer has shown in this brief sample, but the heart of the idea simply remains, as Warren Spahn said so long ago, to upset the timing of the hitter.

#### . . .

Authors note: Neither the present author nor Beyond the Box Score are affiliated with Perry Husband. Additionally, all comments about Bauer's pitch selection are the author's own, and Bauer was not consulted in the production of this article.

All statistics and charts courtesy of Brooks Baseball and the PITCHf/x database. Additional resources for this article were Jason Turbow's longform piece about EV, a fascinating Fangraphs Audio interview with Bauer, and this archived Baseball Prospectus article.

Dan Weigel is a Featured Writer at Beyond the Box Score and an Author of Minor League Ball. Read his tweets at @DanWiggles38