Break in case of emergency catching options
These are the guys that are the bottom of the barrel options at catcher that would be acceptable, but would be pretty disappointing given the better options available on the market. If one of these guys ends up getting the nod, Astros fans better hope that Diaz starts at least 100+ games at catcher in 2024.
Jorge Alfaro has a lot of physical tools that you normally don't see at catcher (he can really run) and he had some nice seasons in 2018 and 2019, but he has not adjusted well to being a backup catcher and has been a well below average player for the last few seasons and struggled to win a back-up job at all last year.
The elephant in the room here is Martin Maldonado who the Astros have shown some interest in despite the fact that Houston didn't give him an extension ahead of free agency. The primary concern in having Maldy around is that the Astros may be tempted to play him far more than they should. However, with Dusty Baker's retirement, there is less of a chance that that would happen if Maldonado were re-signed and he could, in theory, give Diaz the best insight into Houston's pitching staff of all the available options.
That said, it is probably best if Houston looks for better options. Maldy fell off a cliff so badly last year that the intangible benefits of keeping him around on the roster just don't outweigh his current deficiencies on the field on both sides of the ball.