2) Aroldis Chapman
Aroldis Chapman went from one of the most dominant relievers we've ever seen to a pitcher whose career looked like it was on life support after an abysmal 2022 season. Chapman's velocity was down, and he was even left off the Yankees postseason roster after missing a workout.
He'd sign a one-year deal with the Royals this past offseason mainly because most of the league had no interest. Out of nowhere, his velocity peaked back up and he had a 2.45 ERA in 31 appearances for Kansas City. His great half season earned him a trade from the lowly Royals to the division-leading Rangers.
Chapman was incredibly shaky for the Rangers and was part of the team's struggles down the stretch. The Rangers went from a team that looked like they'd cruise to a division title to a team that might've not even made the playoffs. They did settle into a WIld Card spot, but that was no thanks to Chapman (or the rest of their bullpen).
His 3.72 ERA in 30 appearances was decent, but Chapman blew three saves in six tries and took three losses as well (all in separate appearances). He had a 4.81 ERA in save situations compared to a sparkling 1.85 ERA in non-save situations. His struggles have even peaked into the postseason as he had a rough outing in Baltimore saved by a crucial double play ball.
He's been erratic on and off the mound, and his struggles in high-leverage spots raise concern when his role would at the very least be a set-up man for Carlos Estevez if not the team's closer. Plus, there's always concern that at age 36 his velocity will dip once again.