Yainer Diaz

Yainer Diaz, pictured, has consistently produced at the minor league level in his pro career, and is doing the same since a recent call-up to Sugar Land. (Photo from Facebook)

When the Astros’ No. 2 overall prospect, Korey Lee, received his major league call-up last week, there was a good bit of fanfare for what feels like the franchise’s first legitimate potential franchise catcher in nearly a decade.

And with that, it might be easy to forget that there is another one in the minor league pipeline not far behind him who could make some noise sooner rather than later – Yainer Diaz. Diaz is a recent promotee to the Space Cowboys, making his Triple-A debut on June 22 against the Tacoma Raniers.

Diaz, currently ranked by MLB Pipeline as the Astros’ No. 14 overall prospect, earned the promotion after hitting .316 with an .871 OPS and 25 extra-base hits in 57 games for the Double-A Corpus Christi Hooks.

Initial overview

The Cleveland Guardians initially signed Diaz for $25,000 out of the Dominican Republic back in 2016, and he came to the Astros at last year’s trade deadline along with reliever Phil Maton in exchange for Myles Straw.

Diaz has been a steady producer so far in his minor-league career, hitting .321 with an .854 OPS on offense and throwing out 37 percent of potential base stealers through five minor league seasons. Thus far in 2022, he has a .299 average with an .855 OPS across Double-A and Triple-A while throwing out 28 percent of attempted base stealers.

Landan’s lowdown

Despite his consistent production, there have been some doubts about whether Diaz’s performance would continue to translate at the higher levels of the minors and potentially the MLB level despite public scouting reports giving a 60-grade hit tool on a 20-80 scale.

One of the main causes for concern has simply been the quality of contact. Diaz has never punched out very much, with a career 13.8 percent strikeout rate in 1,293 minor league plate appearances – which on the surface, seems a good starting point. But here’s the rub – much of that contact, though hard, is on the ground, with more than 50 percent of his career balls in play being ground balls according to Fangraphs. For context, the MLB average groundball rate this season is 44.9 percent according to Statcast data from Baseball Savant – and Diaz’s has hovered at or above 50 percent for much of his early career.

Ground balls, historically, are the least likely batted balls to result in base hits – so as a hitter, it’s always ideal to be near the bottom of that list. To Diaz’s credit, that rate is down to 42.3 percent so far during 14 games in Sugar Land along with a career-high 26.3 percent line drive rate, so it will be something to keep an eye on moving forward to see if he can sustain it.

Further, Diaz does not draw a ton of walks, with just 66 free passes in those same 1,293 plate appearances – a rate of just 5.5 percent. And while a high walk rate is not necessarily imperative for future success, it does seem as though he could be more selective. Which – in theory – would provide him with better pitches to hit and the ability to elevate the ball more often, and in turn do even more damage.

Defensively, Diaz is renowned for his arm strength, which has been given a 60-grade rating. And he has shown that arm strength time and time again, throwing out nearly 40 percent of base stealers in five seasons. Though admittedly, he has struggled to that end in Sugar Land, throwing out just one of 11 attempted base stealers so far in eight starts.

The rest of his game is very much a work in progress based on what little I have seen of him. But like most things in life, it can easily be improved with repetition – repetition that Diaz figures to get at least for the time being with Lee’s recent major league promotion.


As mentioned above, Diaz figures to be the primary catcher for the short term, with Lee now in Houston while Jason Castro sits on the injured list. And the time is now for the 23-year-old to show what he’s got. Catchers are not typically looked at for their offense – but Diaz could be one of those guys who breaks the mold. As it currently stands, he is an offense-first backstop, which is a departure from the norm for most teams and especially the Astros’ recent history.

Current Astros starter Martin Maldonado remains under contract for next season, but Castro – the backup to begin this season – will be a free agent following this season. And that presents an interesting potential battle between Lee and Diaz to take over that role next season.

Lee has the blue-chip status, but Diaz’s consistent production at each level is (so far) hard to ignore. Throw in the fact that improvement in receiving and blocking and game calling can only come with time and reps, and his struggles there might not be a huge roadblock – especially considering he’d have one of the best in the business in Maldonado to learn from if he does wind up in Houston. Not to mention he has also made 29 starts at first base this season between Corpus Christi and Sugar Land, which potentially lends some extra versatility in the event the Astros do not re-sign Yuli Gurriel.

I would not expect a call-up for Diaz this season. He’s a little raw, and there are already viable players in each of his primary positions. But come 2023, look for Diaz to make at least a cursory impact, either at catcher or first base.

Have a specific player you would like for us to highlight? Email lkuhlmann@fortbendstar.com.

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