Tampa Bay Rays
I think each of the teams on this list are very interesting, but I have been fascinated with a trade idea that our own J.T. Buchheit suggested recently involving O'Neill and the Tampa Bay Rays.
In his story, Buchheit suggested a straight swap of O'Neill for Tyler Glasnow, which almost makes too much sense to me (again, as someone who would rather keep O'Neill in general). Glasnow and O'Neill will both be free agents after the 2024 season, are electric when they are on the field but have struggled with injuries, and play in areas of strength for their clubs.
The Rays have started off the season hot, led by an MLB-best pitching staff, even with Glasnow on the injured list. The saying goes "You can never have enough pitching", and although that is true, no team has both the quality and depth of pitching that Tampa Bay does.
While the Rays' bats have been on fire as well, I think we would all be shocked if they remain a top lineup in baseball throughout the season. They have good bats in their lineup like Wander Franco, Randy Arozarena, Brandon Lowe, and Yandy Diaz, but are currently receiving elite production from guys like Jose Siri, Luke Railey, Isaac Parades, and Josh Lowe as well.
There is surely room to improve their lineup, and O'Neill would offer them a great way to do that. Losing Glasnow shouldn't set them back much at all, as their current five-man group is one of the best in the game and they have multiple top prospects who could factor into their pitching staff as well.
I know Glasnow's injury history scares off people, but that's the risk you inherit with all starting pitchers. Yes, you can argue his history is more extensive than most, but if the Cardinals would deem him healthy at the time of a trade, then it's hard to hold those old injury concerns against him. Especially when it's in a swap for another guy who has major questions about staying on the field in O'Neill.
Even if Glasnow was not the target, the Rays have plenty of other pitching options for the Cardinals to consider.