A former Cy Young winner, Shane Bieber has fallen off significantly from where he was even just a year ago, but his floor is still a very solid starter in this league, and I'd have to imagine he could regain some of his former self as well.
Even if he cannot regain his velocity, Bieber showed in 2022 that he can pitch at a high level with diminished velocity and strikeout rates. He cannot be relied upon as a top-of-the-rotatoin starter anymore, but he'd be a great number three or could potentially mask as a number two.
Similar to the Rays, the Guardians will likely want to move off Bieber early this offseason in order to free up salary from their books. The Guardians are going to want to upgrade their offense, so a deal involving Tyler O'Neill or Dylan Carlson makes a ton of sense.
Obviously, Bieber isn't the most exciting starter they could acquire. But if they could acquire him at a low price point and ensure they have already made one of their pitching upgrades, it could be worth grabbing a starter soon.
It's not for certain that the Guardians are moving Bieber, but it would make a lot of sense for the Cardinals and to swing a deal if they can in the coming days.