Elias Díaz Settles in Colorado

Though this year’s market for catchers is pretty barren, so much so that Pedro Severino was a solid pickup for the Brewers, the 2023 free agent class is much more fertile. Several notable catchers will be available for teams to vie for, including Max Stassi, Willson Contreras, and Mike Zunino. Rather than wait the extra year, however, the Colorado Rockies seem content with their in-house options, last week handing veteran backstop Elias Díaz a three-year extension worth $14.5 million. The contract covers his remaining year of arbitration and two seasons of free agency.

In so doing, the Rockies have effectively announced their intent to stick with Díaz rather than search for a new everyday catcher; Dom Nuñez will likely occupy a backup role, while Drew Romo, the team’s No. 3 prospect according to our 2021 rankings, is still a couple of years away from his big-league arrival. All things considered, Díaz had himself a solid season. His 1.6 WAR ranked 15th among 30 catchers with at least 300 plate appearances, making him just about a smack-dab average backstop. Assuming Díaz can keep up this level of production, an AAV slightly under $5 million is a green light, more so because of the relative scarcity of reliable alternatives.

But of course, it’s more complicated than that. In 2019, his previous full season, Díaz was one of the worst catchers in the league, with a 61 wRC+ and a negative value in just about every defensive metric; he was non-tendered by the Pirates that offseason. His track record before that isn’t impressive, either – though Díaz accrued 1.8 WAR in 82 games in 2018, his ’17 campaign was disastrous, good (?) for -1.2 WAR. The Rockies are betting that this back-and-forth parkour will stop, and that the Díaz of the present will be who Díaz remains in the future. It’s a bit risky, though. Which version of Díaz is more likely to appear next season, and can we make an educated guess using the numbers?

Let’s start with his bat. Díaz started the 2021 season on a troublesome note; through the month of May, he had a .125/.193/.188 triple slash line with just a single home run and a -8 wRC+. Instead of cutting Díaz, though, the Rockies kept the faith. It paid off big time: Díaz would go on to hit .283/.346/.550 (123 wRC+) the rest of the way, completely turning around what otherwise looked like a doomed year.

As for what he did differently, well, manager Bud Black has mentioned Díaz’s physical strength and durability. And yes, those things definitely mattered. They can’t be easily measured, but perhaps they helped forge this simple trend. In the second half of last season, Díaz started hitting the ball in the air way more often:

His fly ball rate and wOBA go hand in hand, which isn’t too surprising to see. In fact, Díaz might be a hitter who can make the most of Coors field – his batted ball numbers aren’t the flashiest, but he’s shown a modest amount of pop throughout his career. Moreover, the thin Denver air means Díaz doesn’t need top-end exit velocities to produce extra-base hits. If he can continue elevating the ball with the requisite amount of force, which his home arena lowers, a 20-homer season doesn’t seem out of reach.

On the other hand, we now know that changes to a hitter’s launch angles aren’t necessarily permanent. Habits are difficult to change, and elevating isn’t for everyone. Consider Eric Hosmer, who briefly seemed to tap into his slugger potential in 2020, only to revert to his old form the following season. Or Christian Yelich, who once served as a poster boy for the launch angle revolution but is now back to his pre-2018 self, though in his case injuries are likely a massive culprit.

Then there’s the matter of how Díaz will perform behind the plate. Once a terrible pitch framer, he’s become decent in recent seasons, raising his strike rate on borderline pitches from 44.6% in 2019 to 47.1% in ’21. It might not seem like much, but according to Baseball Savant, the former rate cost Díaz’s team 10 whole runs; now, his receiving at least isn’t a liability.

But I remain skeptical of one-hit framing wonders, and here’s why. As a test, I figured out which catchers improved their strike rates the most between 2017 and ’18, then looked at how they fared in ’19. Basically, how sustainable are improvements to framing? My results were mixed. On average, the nine catchers I measured, ranging from Alex Avila to Zunino, lost approximately 1.9 percentage points of strike rate in 2019 following an improvement in ’18.

That doesn’t mean every catcher got worse. Jonathan Lucroy, for example, gained an additional 1.2 percentage points. And an obvious caveat is how limited my sample was, as finding catchers who play regularly for three consecutive seasons is surprisingly difficult. But it does seem necessary to sprinkle in some “regression” to a catcher’s framing numbers. In Díaz’s case, it might signal a reversion to his former self, which the Rockies are banking won’t occur.

Pitch framing isn’t everything, though. Díaz also managed to throw out 42.1% of would-be base-stealers last season, placing him second behind Salvador Perez (43.9%). And indeed, a portion of his 1.6 WAR can be attributed to Díaz’s marksmanship. But here’s one curious detail. Prior to writing this article, I assumed that he had become faster at throwing out runners, and therefore better at throwing them out. To my surprise, however, Díaz always had a strong arm – he averaged an exceptionally good pop time of 1.93 seconds in 2019, when he recorded a success rate of 26%. Huh. Something didn’t add up.

Except… the effect of a catcher’s arm on controlling the running game isn’t as great as one might think. There’s a great article by Max Weinstein I always go back to, which demonstrates that pitcher release times are what primarily determine the outcome of a stolen base attempt. Have a faster delivery, and chances are runners will run out of time before arriving at second base. We also know pitch location is a factor, too – a fastball up and away is easier for a catcher to handle than a breaking ball down and in. Did the Pirates’ pitching staff, which (in)famously insisted on sinkers during the 2010s, somehow mask Díaz’s ability to throw out runners? Who knows! Maybe the Rockies have helped him unlock his potential. If there’s reason to believe this isn’t a coincidence, there’s also reason to believe an extension is justified.

It won’t cost the Rockies too much even if Díaz ends up a bust; spread out over three seasons, $14.5 million is pocket change compared to what this year’s marquee free agents will receive. Even so, I do think there’s an element of risk. If all three components of Díaz’s game – offense, framing, throwing – come together, the Rockies will have themselves a bargain. Two out of three would still represent a success. With only one, though, the extension won’t look as pretty, and what’s even scarier is the real possibility of getting zero. Díaz has been, well, not good before, and finds himself on the wrong side of 30.

Nevertheless, the stakes here remain low. The Rockies are presumably confident about what Díaz’s true talent is. Díaz presumably wanted to remain in Colorado. There’s a match here, one I don’t blame either side for committing to. Hopefully, its ending is as benign as its beginning.