Well, Ramirez was literal garbage last year and plenty of clubs haven't found him to be worth a roster spot, so "marginal upgrade" may be the most flattering way you could put that move. I hate Tepera but even if he's worth nothing in the clubhouse, it's probably not worth showing players that they're basically livestock to swap them out for guys who probably suck just as much.
Besides, Ramirez will probably make it through waivers so they'll likely still have the option to switch him out with Tepera if they really need to.