Although they are amicably referred to as the Twin Cities, Minneapolis and St. Paul have starkly different personalities. Minneapolis is more of the livelier twin, known better for its skyline and nightlife. St. Paul is all business, being the capital of Minnesota and all. Like Minneapolis and St. Paul, Ryan Jeffers and Christian Vázquez stand together as Twins but with clear distinctions. Jeffers’ absurd power differentiates himself, whereas Vázquez’s defensive instincts have bestowed him recognition around the league. To no one’s surprise, these two backstops have contributed in different ways for the Minnesota Twins.
Jeffers’ 135 wRC+ dwarfs Vázquez’s 69. Jeffers’ offensive prowess has predominantly come from his slugging and on-base percentage. Meanwhile, Vázquez has accrued 9.6 defensive wins above replacement. Jeffers currently has only 0.6.
It is these differences that necessitate a closer look. The recipe for winning baseball games is simple; score more runs than the bad guys. The steps taken during that process are plentiful. Some lineups are filled with adept contact bats, others are loaded with power mixed in. Of course, fielders can contribute to the team’s success in multiple ways with their bats and their gloves. That extends to catchers, where quantifying defensive ability is not quite as easy as it can be for their infield and outfield counterparts.
Defensive Runs Saved (DRS), Ultimate Zone Rating (UZR), and Outs Above Average (OAA) are three premier defensive stats analysts and fans use to assess defensive skill. Sure, there are some easily measurable stats for catchers. Arm Strength and Framing come to mind, but the primary duty of a catcher is how they call a game. There is no stat to measure that, at least none that are widely accepted and circulated. Arm Strength and Framing still factor into the talent level of a catcher, and I will not gloss over them during this comparison.
Base stealers find higher-than-average success against Vázquez and Jeffers. Vázquez has allowed one more stolen base than an average catcher. However, Jeffers has allowed even more (four).
Vázquez’s defensive reputation is not undeserved. He’s prevented about two runs this season thanks to his excellent pitch framing. Jeffers has allowed one more run to score than the average catcher due to his subpar framing.
Wishing to take a statistically holistic approach in a comparison between these two, there must be a stat that encapsulates game-calling. How would one measure how well a catcher is calling a game? It is surely more straightforward to measure game-calling when comparing one catcher to another. The stats of a pitcher with one catcher compared to a second catcher is a good start.
The results of each pitch is not something the catcher can control. Neither is the pitcher’s command. But a great catcher can study batters effectively, discern their weaknesses, and understand both the batter’s body language and the pitcher’s current control to minimize the number of runs scored.
If you’ve read some of my previous articles, you know about my propensity for PitcherList’s Pitch Level Value (PLV) and Tom Tango’s work. The reasoning behind PLV is strong. Essentially, PLV’s highly-graded pitches will be fast, move a lot, and be thrown in the “correct” spots against the correct-handed batter in the right counts.
Much of Tango’s work has to do with Run Expectancy. Teams with runners on second and third with no outs are probably going to score more runs during their ensuing at-bats than a team with two outs and nobody on. Should a batter swing and miss amidst the former example, absolutely zero runs will score. If the batter makes contact in the air, there’s a decent chance a runner will score. It’s this kind of thinking that can be applied to game-calling.
Statcast’s delta Run Expectancy (change in Run Expectancy before a pitch and after a pitch, hereby denoted dRE) is of particular interest. Unfortunately, dRE does not apply the same line of thinking as PLV. A catcher could call for a tempting slider that just barely drops below the zone won’t be rewarded, even if it made intuitive sense during the at-bat. (Perhaps it was called in a 1-2 count where the batter was clearly timing for a fastball.) dRE will have to suffice here.
Using data provided by Statcast, the dRE of every single Twins’ pitch can be summed and divided by the number of pitches thrown to find the average number of runs a catcher adds/subtracts per pitch. I looked at six Twins pitchers: Joe Ryan, Bailey Ober, Kenta Maeda, Sonny Gray, Louie Varland, and Tyler Mahle. On each pitch, the player catching it is also recorded, resulting in 12 pitcher-catcher pairs. We can look at how many runs Jeffers adds or subtracts when catching for Ryan and how many runs Vázquez adds or subtracts.
Below is a plot of the final product
As one would expect, Vázquez is clearly seen as the superior game-caller. In a (Minnesota Twins) typical 85-pitch game, Vázquez is expected to prevent about 1.13 fewer runs from scoring per game than Jeffers (exact numbers in the chart below).
Game-calling’s eventual inclusion will be important to the effort to create an all-encompassing baseball statistic. Comparing Jeffers and Vázquez on FanGraphs is an excellent way to declare the better player (Jeffers). But remember that catcher defensive WAR does not factor game-calling in. Jeffers may be better statistically with his 1.4 total WAR to Vazquez’s 0.6, but the full value of Vazquez’s defense is not yet known.
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