Tyler O'Neill (trade)
The final player on this list is the one who had the highest ceiling of the players whom the Cardinals lost this offseason: Tyler O'Neill. O'Neill's presence in St. Louis was starting to wear on fans, and his scuffle with Oliver Marmol at the beginning of the year likely hurt his case to receive a decent workload in 2024.
O'Neill, a free agent after this year, was always a player who could have an MVP-type season. He proved that in 2021, a year in which he hit .286/.352/.560 with thirty-four home runs and a 148 OPS+. O'Neill also won a Gold Glove in left field that year. The next two seasons were marred by injury for the strong outfielder, and he was seen as a player who needed a change of scenery.
Therefore, St. Louis traded him to the Boston Red Sox for Nick Robertson and Victor Santos, two pitchers. Robertson will be in the bullpen mix for 2024 while Santos continues to develop in the minors. This trade was a bit interesting to fans, as most expected O'Neill to net a higher-end prospect or a more proven reliever, but John Mozeliak likely squeezed whatever value was left out of Tyler O'Neill.
O'Neill was always a tantalizing player. He was a constant threat as a batter due to his plus speed and his plus power tool. Given a fully healthy season, there was always a chance he could return to form. Lars Nootbaar, Tommy Edman, and Jordan Walker are going to get a full run in the outfield next year; Dylan Carlson, a former top prospect who had a good 2021 season, will be the team's fourth outfielder.
This depth led O'Neill to be the odd man out, and he wasn't going to get much playing for the Cardinals. However, in O'Neill's recent interview with the guys at Foul Territory, he stated that his back feels great for the first time in years. His health could rebound next year, and we as Cardinal fans could be watching a Tyler O'Neill revenge tour with the Red Sox.