I imagine this headline might infuriate some people. But there’s plenty of explaining to do. When the news surfaced that the Royals may lose Salvador Perez, their World Series MVP, perennial All-Star and Gold Glover, and face of the franchise, for the season, their was plenty of reason for fans to be sad. Losing a good catcher on and off the field, along with a player that was a driving reason for many fans to even watch or show up to games is not a good thing.

But if you look deeper, you can find many reasons on why this isn’t such a terrible outcome. For starters, it may be good for Perez himself. Giving his knees a full-season rest in a season that most likely will amount to nothing is a positive. Second, I don’t think the Royals are losing much “on-field” value here, bringing in veteran catcher Martin Maldonado on a one-year deal. Third, if all goes well, this could amount to some value at the trade deadline.

If you’re a casual fan and you judge players with the eye-test, you’re taking Perez over Maldonado eleven times out of ten. Perez has the advantage in most recognizable areas. He’s by a superior overall hitter, he hits for far more power, and by most accounts, his glove behind the plate is at an elite-level. Counteracting with Maldonado, he’s a worse hitter (career 72 wRC+ vs Perez’s 97). He doesn’t hit as many home runs (51 vs 141). Looking to the glove though, they are comparable (Maldonado was worth 11.3 defensive runs above average in 2018, Perez 10.7). You may even remember him edging out Perez for the Gold Glove award in 2017, ending Perez’s four-year run, rightfully so.

Judging off that quick comparison, Perez looks like the better player. But there is still a very important aspect of the catching game that I haven’t gotten to yet. Framing. Easily one of the more important areas that a catcher can excel in, yet one of the least recognizable talents for watching fans.

Do give you a quick run down on framing, here’s the definition Baseball Prospectus has instilled for their metric that measures it.

The specified details of the CSAA mixed models are in the Appendix. The Reader’s Digest version is as follows: the model considers each and every pitch thrown in the major leagues each season. For each pitch where a batter did not swing, we input (1) whether the pitch was a ball or strike (our output variable), (2) our various participants: the pitcher, catcher, batter, and umpire, which are our “random effects”; and (3) our chosen “fixed effects” we found to be meaningful: the PITCHf/x probability of the pitch being strike, the handedness of the pitcher and batter, and whether the team was playing at home or away. All of these fixed effects have a statistically significant effect on the likelihood of a pitch being a strike. For CSAA, we ran the model separately for each season from 2008 to the present time, and collected each season’s results.

To break down the framing numbers incorporated into overall defensive value between Maldonado and Perez in 2018, I’ll prorate their Fielding Runs Above Average (FRAA) to 120 games.

• Maldonado: 119 games, 3.1 FRAA, 3.12 FRAA/120 games
• Perez: 129 games, -8.1 FRAA, -7.53 FRAA/120 games

The difference in framing is huge between the two. Perez is generally considered a terrible framer, severely hampering his value. Maldonado on the other hand is considerably above-average in the department, making him an underrated asset. This changes this gap in overall value, even with hitting and other defensive aspects considered (looking at WARP), as Maldonado very well might be the better player

• Maldonado, 2016-18: 333 games, 6.2 WARP, 2.23 WARP/120 games
• Perez, 2016-18: 397 games, 5.1 WARP, 1.54 WARP/120 games

Now you may be asking why framing is such a big deal and how the Royals are impacted by this. To break it down in easier terms, I’m going to look at the rates in which both catchers assist their pitchers. There’s two things you can look at to easily identify this. Out-of-zone strike% and in-zone ball%. Narrowing a sample size to a minimum of 2,000 pitches caught in 2018, I’ll start with out-of-zone strike%. Out of 67 qualified catchers, Maldonado ranked sixth. Last year he ranked sixth and in 2016 he ranked 12th. He’s consistently good at helping his pitchers get strikes outside the strike-zone.

First Name	Last Name	Year	Team	Sample	oStr%
Austin	Barnes	2018	Dodgers	3501	11.1
Jeff	Mathis	2018	D-backs	4589	10.9
Raffy	Lopez	2018	Padres	2215	10
Luke	Maile	2018	Blue Jays	4839	9.5
Yasmani	Grandal	2018	Dodgers	8479	9.4
MARTIN	MALDONADO	2018	Astros	2473	9.4
Max	Stassi	2018	Astros	5004	9
Roberto	Perez	2018	Indians	4149	8.8
Tyler	Flowers	2018	Braves	5436	8.8
John Ryan	Murphy	2018	D-backs	4053	8.6

Perez is the opposite. Last season, he ranked 51st out of the 67 qualified. In 2017 he ranked as the second worst catcher. In 2016 he was the worst catcher. Terrible. Here are the 20 worst catchers in this for 2018.

First	Last	Year	Team	Sample	oStr%
Isiah	Kiner-Falefa	2018	Rangers	2576	4.2
Jesus	Sucre	2018	Rays	4203	4.7
Andrew	Knapp	2018	Phillies	3427	4.8
Austin	Wynns	2018	Orioles	2838	4.8
Curt	Casali	2018	Reds	2424	4.9
Grayson	Greiner	2018	Tigers	2365	4.9
Omar	Narvaez	2018	White Sox	6101	5.2
Drew	Butera	2018	Royals	3429	5.3
Francisco	Arcia	2018	Angels	2128	5.3
Francisco	Pena	2018	Cardinals	2796	5.4
Devin	Mesoraco	2018	Mets	4083	5.5
Matt	Wieters	2018	Nationals	4652	5.6
A.J.	Ellis	2018	Padres	3366	5.6
Welington	Castillo	2018	White Sox	3397	5.6
Kurt	Suzuki	2018	Braves	6775	5.8
SALVADOR	PEREZ	2018	Royals	7541	5.8
Caleb	Joseph	2018	Orioles	6435	5.8
Chance	Sisco	2018	Orioles	3322	5.9
Francisco	Cervelli	2018	Pirates	6907	6.2
Spencer	Kieboom	2018	Nationals	3135	6.2

Looking to the other side of things, in-zone ball% (you want to have a lower-rate), Maldonado was again, pretty good. In 2018 he ranked 14th out of 67. In 2017 he was fifth. In 2016 he was 20th. Here were the top 20 catchers from last year.

First	Last	Year	Team	Sample	zBall%
Sandy	Leon	2018	Red Sox	5818	9.5
Max	Stassi	2018	Astros	5004	10.8
Pedro	Severino	2018	Nationals	4302	11
Roberto	Perez	2018	Indians	4149	11.2
Christian	Vazquez	2018	Red Sox	5552	11.3
Gary	Sanchez	2018	Yankees	5666	11.4
Jorge	Alfaro	2018	Phillies	7394	11.5
John Ryan	Murphy	2018	D-backs	4053	11.7
Grayson	Greiner	2018	Tigers	2365	11.7
Luke	Maile	2018	Blue Jays	4839	11.9
Russell	Martin	2018	Blue Jays	5665	12
MARTIN	MALDONADO	2018	Astros	2473	12.1
Brian	McCann	2018	Astros	4049	12.1
Tyler	Flowers	2018	Braves	5436	12.2
Austin	Hedges	2018	Padres	6293	12.2
Yan	Gomes	2018	Indians	7784	12.3
Bobby	Wilson	2018	Twins	3398	12.5
Austin	Romine	2018	Yankees	5502	12.5
Matt	Wieters	2018	Nationals	4652	12.5
Austin	Barnes	2018	Dodgers	3501	12.6

For Perez, again, not good. Last year, he had the fourth highest rate. In 2017 and 2016, he respectively had the 17th and 22nd highest rates. Here were the ten worst from 2018.

First	Last	Year	Team	Sample	zBall%
Isiah	Kiner-Falefa	2018	Rangers	2576	17
Manny	Pina	2018	Brewers	6604	16.4
Nick	Hundley	2018	Giants	5714	16.2
SALVADOR	PEREZ	2018	Royals	7541	16
Tucker	Barnhart	2018	Reds	8712	15.9
Welington	Castillo	2018	White Sox	3397	15.8
Victor	Caratini	2018	Cubs	2670	15.6
Jose	Briceno	2018	Angels	2628	15.6
A.J.	Ellis	2018	Padres	3366	15.5
Kevin	Plawecki	2018	Mets	5107	15.4

All stats courtesy of StatCorner

These lost and added calls for the pitching staff add up over thousands and thousands of pitches. For perspective, Maldonado has added 146 calls for his pitchers the past three seasons. Perez has lost 515 (!!!) calls in that same time, by far the most in baseball.

For visual effect, here’s a heatmap of each catcher’s called strikes the past three seasons.

Or in form of GIF. Here’s Maldonado using his skill to pull a ball slightly up into the zone, presenting it well for the umpire. It was tracked outside the zone, but called a strike to end the game.

Here, on a pivotal 3-2 count, he does the same thing to net his pitcher a strikeout.

Varying in certain counts and situations, this can have a enormous impact in an at bat, a game, or even a season. For example, a lost strike to begin an at bat can be a swing of nearly a tenth of a run. That adds up over the course of a long season.

https://twitter.com/tangotiger/status/1100464626498711554

Having Maldonado become the Royals starting catcher will theoretically help a lot of pitchers on the Royals staff. The added advantage for the younger arms on the staff is a nice compliment too. The injury to Salvador Perez is a very unfortunate blow to the franchise and to the season, but don’t be surprised if the pitching staff and the Royals come out looking better because of it.

Photo Credit: MLB.com