It's unfortunate but not surprising. Thomson says he's still in semi-rehab mode which Ranger blanched at, but even aside from that it seems safe to say he's not 100%.. And he'd thrown more innings than he ever had in his career before he got shut down (now he will only barely top 2022). And yeah, there's a slim margin of error there that probably couldn't last forever. He's just back to being a #4 who can hopefully pitch like a #3 (especially with careful usage), same as the last two years (remember, Eflin and Walker started the last two seasons as the ostensible #3s, and Ranger wasn't durable, which is also why Walker was an overpay).
But now at least there'a Sanchez.