The Best Catcher in Free Agency (Not Named Realmuto)

There are few things in baseball worth more than a star-level catcher. Playing a position that requires you to squat each day for a 162-game season makes for a lot of injuries and shortened careers, and the role of a catcher is so crucial between game-calling, baserunning control, framing, and blocking, that just playing your good defense and being pitcher-friendly will get you a long career no matter how horrible you are with the bat.

Fortunately for all teams in need of a receiver, the 2020 free agent market offers one of the rarest cases among the sport, a true five-tool catcher: J.T. Realmuto, the former Marlins and Phillies backstop, is available for his mere salary.

You want a steady bat, maybe with some thump? Realmuto walks in sporting a career .278 AVG, .455 SLG, and double-digit homers in each of his six “full” seasons in the league.

You need a reliable asset, one that punches the ticket and goes to work? He averaged over 130 games from 2015-19.

You need a rock-solid defender that can also help your guy on the mound? J.T. is there for you with a rocket arm (over 88 mph on his average throw) and a spotless fielding percentage, and while he’s behind the plate, he’ll steal strikes for your pitchers as a 95th-percentile framer does.

Heck, he’ll even run if you ask him to, dashing at over 28 mph, making him an 84th-percentile runner, an absurdity given his role on the field.

The demand for Realmuto is boiling, and understandably so as a lot of teams have a glaring hole in the catching department: the Phillies would like him back, the now Cohen-owned Mets are ready to splash some cash, the Padres could do adding a star to a talented core, and so would many franchises, but just the one will have him at the end, and at a price that may comfortably jump the $20M AAV for 5-plus years.

But what’s left after him? The Mets already decided to spend their money on James McCann, a solid bat with recent defensive improvements. There’s also ex-Red Curt Casali, a potent bat but questionable fielder behind the dish, and Cardinals legend Yadier Molina, not a force with the stick but a game-changer in his spot.

Do they hold up against Realmuto? Let’s have a look!


When we look at their 2020 stat lines, Realmuto is the best, but the competition McCann poses is closer than it may seem! Realmuto has the higher EV and Barrel%, but McCann has the better HardHit%, and they have similar contact profiles — although the former Phillies catcher can also run, gun down stealers, and steal strikes himself, so the gap should widen considerably on a full-season scope. Molina had a nightmare line for a batter, and the half WAR he brings is a testimony to his defensive marvel. Casali is an interesting option: his slugger profile includes a Hard% and ISO that are the best of the group, but his acute flyball tendencies means he also gets under a lot of balls (see the high LA and low BABIP), so that his Barrel% is behind both Realmuto and McCann.

This is where I come in and tell you why I chose those stats, and that is because, as usual, I want to propose someone not on the radar, a guy that is making unique choices and deserves a look:


Look at Mister X! This is Curt Casali with the Barrels! There’s nothing not to like: he walks more than average, and he hits balls hard more than half of the time and predominantly in the air. Oh, by “hard” I mean that he destroys them: his EV is almost 2 full mph more than Realmuto, his LA sits at a dreamy 20°, his HardHit% blows away the competition, and that sweet Barrel% grazes 15%, something only batters with 20-30-homer power can do. Also, a hint for you: he hits from the left side of the plate.

Did you guess right? Mister X is none other than former Astro, Angel, and Padre, Jason Castro.

Wait, what? The same Castro who was once a defensive wizard, caught-stealing machine, and All-Star is now a three-true-outcome savant!?

Castro began last year with the Angels and was traded midseason to the Padres for reliever Gerardo Reyes, where he formed a tandem of catchers arrived via trade with Austin Nola. The fact that a team in contention like San Diego wanted him shows that he’s doing something right, although not too much considering his WAR ended at an unspectacular 0.3.

Was last year a new edition of Castro, or rather was all of that due to a small sample size in terms of PAs and events? Not so fast! Here is Castro from 2018-20:


Castro started hitting the ball much harder in 2019, in the realm of a 4-mph increase with respect to his previous career average, and his production followed suit: he posted an above-average wRC+ (103) for the first time since 2013 (129).

Is this newfound hitting prowess something out of nowhere or a result of some specific choices by Castro? As you may guess from looking at his plate discipline stats from 2018-20, it’s more the latter.


One thing stands out: Castro is making much less contact than before — less than 70% in both 2019 and 2020 when his previous career average was around 75% — while also swinging and missing more, which is not a desirable combo unless it is a sign of maximizing damage.

That’s the element of pitch selection. Castro is the one who’ll wait for his preferred offering instead of swinging early, something suggested in his fourth-lowest Z-Contact% among batters with at least 80 PAs in 2020, as well as a first-pitch swinging% of just 27%.

Here’s Castro’s swing/take profile from last year:


Note that his diminished contact rate is the only strange dot compared to his career’s picture. He never swung a lot at pitches outside the zone nor in, and in general he roams around a 45% swing rate; he’s seeing less pitches in the zone as of late but nothing critical, and the only thing that’s changed is his intention at the plate, one that is now all about hitting certain pitches as hard as possible. That means taking a lot of offerings in the corners and even in good places to hit if they are not the “chosen one,” a search for the perfect pitch to hit that could be losing him some value due to inaction, a trait pitchers are exploiting by throwing him an above-average rate of pitches in the shadow zone where he’s far below average in swing rate.

Is there any kind of specific trouble for Castro in terms of pitches thrown against him? Here is his value per pitch type from 2018-20:


You could think that he’s another one of the guys blown away by the heat, but if we considered his value per 100 pitches, he would actually be only slightly in the red, nothing that screams diminishing bat speed or fastball aversion. Look at how he performs against the cheese:


His swing, contact, and damage profiles are matching, showing that he has a grasp of what to do with a fastball and where his nitro zone is: he swings less in the upper part of the zone, where his bath path is not as conductive leading to less and worse contact, but boy can he destroy the middle-in heat! He is deadly both in the heart of the plate and near the inside corner, swinging a lot and for power, while in the middle-away and low part of the zone he gets less rewards and more risks.

He is a capable fastball hitter altogether; his expected results against the heat in 2020 were great, from a .256 xBA to an astounding .570 xSLG, a solid .372 xwOBA and an EV at over 94 mph, all with a still-acceptable 24.5% whiff rate.

The real issue with Castro is the old yacker, the bender, commonly known as the curveball. His value with the curve is almost as bad as the one with the fastball in a third of the pitches, resulting in a value per 100 that is the 15th-lowest in all of 2020 baseball.

Is Castro simply unable to lay off the low curve in the dirt or what?


Well, not really! He is swinging at a lot of curveballs wherever they are, and he is not hitting them at all. By the way, why is there no ISO graph? That was me being kind: simply put, that would have been a splash in the ocean, just a big blue square with a bunch of zeroes as Castro wasn’t able to do anything with the few Uncle Charlies he hit.

How bad was he in the curve department? Looking at Savant is a horror story: for breaking balls (curves and sliders), Castro saw his expected stats range from a .181 xBA to a ghastly .338 xSLG, not to mention a horrid .270 xwOBA and a 41.7 Whiff% as the cherry on top of a cake not suited for eating.

To close his pitch profile, he was almost equally as bad against changeups, whiffing at over a 50% clip but with some bad luck, while he was 12th-best against cutters per 100 pitches, something suggesting that Castro prefers pitches boring in rather than down or away (the Savant stats for fastballs already include cutters).

What about his other source of value, his ability behind the dish? It’s a tricky evaluation, one that flutters depending whom you ask to or where you get the data from.

One thing is set in stone: Castro is a good framer, hovering around the 70th percentile and amounting for 1-2 runs gained through strike-stealing in an entire season. That’s not much but still something you’d rather have than not. In particular, he displays above-average strike rates for both corners and down the zone, a trait he always had but on a greater degree between 2015-16, amounting for a total 22 runs gained by framing.

As for the other aspects of the defensive spectrum, there’s not that much clarity: his arm, once a cannon erasing up to more than 33% of base-stealers, is now standing on a quieter-yet-acceptable 20-24% given a good exchange time (0.74s) but only decent arm strength (82.5 mph on average, almost 6 less than Realmuto). His game-calling, raved about by many pitchers, is not as strong as the rCERA component according to Fielding Bible, as it is in the negatives for his third year in a row.

All things considered, Castro’s defense is still solid enough to provide positive run value in the WAR calculation driven by framing, run suppression, and the always generous positional adjustment.

Finally, there is his contract. Taking the McCann-Mets deal at the murmured $10M AAV for four years as baseline, Castro is set for a much shorter and less remunerative payday, but that also means he could be a value bet for almost everyone.

Strong teams with holes at the catching position, such as the Phils along with the Cardinals and the Nats, could strike a bargain and reroute their expenses towards some pitching; solid teams that already have a catcher but could build a platoon tandem, such as the Astros with Martín Maldonado and the Yankees with Gary Sánchez, could opt for a sign and (future) trade if Castro provides the rare lefty thump at catcher.

Either way, Castro will probably get a one-year contract around $5-8M, a solid-to-great deal for a guy who is a sole season removed from a 1.6 WAR exhibit in only 270 PAs or so.

Jason Castro was an All Star, a defensive stalwart with some power, then years went by, his old M.O. started to show signs of decline, and he took a bold decision: changing his approach at the plate to squeeze every bit of pop out of his bat, sacrificing contact and hits so that, pairing it up with a solid contribution behind the dish, he could still be a valuable piece for a contending team.

He’s going to sit dead red middle-in, let some strikes go by, and maybe miss a lot of those nasty breaking balls, but he’ll give you double-digit homer potential lower in the lineup, ready to crush the poor righty starter looking for a breather. And when he’s brought the average bat home, he’ll pick up the tools of ignorance, frame a ball for a strike here and there and gun down one out of four runners if need be, all of that at a price that makes him available for every pocket, from the poorest to the richest of franchises.

That is why, bang-for-buck, despite taking too many pitches and swinging-and-missing more than average, Jason Castro is the best catcher in the market not named J.T. Realmuto.

All tables and heatmaps can be found in the leaderboards section of FanGraphs, while expected statistics, swing/take ratios, and zones are available on Baseball Savant.

I'm an Italian baseball fan. After watching Moneyball I got into statistics and graduated with a master in Data Science. Now I'm about to start BaseX, the Italian Center for Sabermetrics in collaboration with IBL and Fortitudo Bologna. Meanwhile I'm learning new languages, hoping one day to work for a team in the Far East.

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