Yesterday, the White Sox traded Gregory Santos to the Seattle Mariners for outfielder Zach DeLoach, pitcher Prelander Berroa, and the 69th overall pick in the 2024 draft. My colleague Mitchell Kaminski elaborated on the return from this trade and the Cristian Mena for Dominic Fletcher trade.
The thought process behind trading Santos is unclear to some, which is understandable. After all, he blossomed into an elite reliever in 2023. That claim is not debatable, as Fangraphs rated him as the 12th best reliever in all of baseball this past season by fWAR. Santos is sandwiched between Josh Hader and Clay Holmes on that leaderboard, a testament to his excellent season. His 2023 campaign was right up there with some of the best relievers in the sport. Santos’ breakout season doesn’t appear to be a fluke either, as his Baseball Savant page is an absolute thing of beauty and supports the claim that he is elite now. His percentiles are exceptional across the board in categories such as fastball velocity, barrel percentage, chase percentage, and ground ball percentage. He is also only 24 years old and will not be a free agent until after the 2028 season. Santos is a fantastic long-term addition to the contending Mariners bullpen and will likely slot in as the 7th or 8th inning man in Seattle.
However, there are also some reasons for concern. Santos had a 4.79 ERA in the second half of the 2023 season compared to a 2.76 ERA in the first half. In August and September specifically, he had an ERA of 6.00 and a 1.47 WHIP in 14 appearances. However, these numbers should be taken with a grain of salt, as 2023 was his first season as a full-time reliever at the MLB level. He might have just been fatigued in the dog days of summer, as he had never pitched that much in one season before. However, this dropoff in the 2nd half shows the somewhat volatile nature of relief pitchers. Relievers can be elite one year and fall off a cliff the next. Perhaps the White Sox think he will regress some moving forward, which could explain why they pulled the trigger on this trade. It is also worth noting that the Sox will not be good in 2024, so having an elite reliever on the roster is not that important to a team that will not be competing for anything significant.
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Santos also has injury concerns. He went on the injured list last September with right elbow inflammation, which is always a scary development for pitchers who throw very hard and have devastating offspeed pitches like Santos. This injury was significant enough that Chris Getz expressed concerns this past December about his availability for the start of spring training. Hopefully, this elbow issue does not develop into a long-term problem, but this aspect of his situation is worth mentioning. It could also be a possible explanation as to why the White Sox decided to part with him.
The combination of the White Sox being a terrible baseball team, potential injury concerns involving his elbow, and the volatile nature of relief pitchers are all justifiable reasons to trade an elite reliever with a lot of team control in Santos. Chris Getz parlayed him into another reliever who will likely replace him in the bullpen, an outfielder who will probably see at-bats at the MLB level in 2024, and a draft pick that will add another young player to the system. Of course it remains to be seen if this trade will pan out as hoped, but the thought process behind this trade from the White Sox perspective is understandable.