Mariners and White Sox swap former SF Giants prospects in four-player trade

A pair of former SF Giants high-octane pitching prospects swapped organizations in a trade between the Chicago White Sox and Seattle Mariners.

A pair of former high-octane SF Giants pitching prospects changed organizations in a trade between the Seattle Mariners and Chicago White Sox on Saturday. The Mariners traded right-handed pitcher Prelander Berroa, outfielder Zach DeLoach, and the 69th overall pick in the 2024 MLB Draft to the White Sox for right-handed pitcher Gregory Santos. Both Santos and Berroa were once pitching prospects in the Giants organization with promising pitch arsenals.

SF Giants relief pitcher Gregory Santos throws a pitch. (2022) / John Hefti-USA TODAY Sports

Santos, the clear centerpiece of the trade, is coming off a breakout season with the White Sox. As a 23-year-old rookie in 2023, Santos emerged as one of Chicago's best relievers, recording a 3.39 ERA (2.65 FIP) with 66 strikeouts and 17 walks in 66.1 innings pitched (60 games). With the White Sox expected to be a cellar-dwellar once again in 2024 though, they opted to trade him to the Mariners for several young pieces.

Santos was acquired by the Giants in a trade with the Boston Red Sox back at the 2017 MLB trade deadline as part of the package for Eduardo Núñez. Originally a starting pitching prospect, Santos was moved to the bullpen by the Giants in an attempt to expedite his development following the cancelled 2020 minor-league season.

Upon Santos' return to the minors in 2021, he posted a 4.99 ERA across 48.2 innings pitched (47 appearances) with 49 strikeouts and 29 walks at Triple-A over the next two seasons. He's also made five big-league appearances with the Giants, recording five strikeouts and five walks in five appearances with an 11.12 ERA. 

Despite his mediocre numbers, he was still quite young with a fastball that had reached 100 mph, a promising slider, and a minor-league option remaining. Still, San Francisco opted to trade him to the White Sox last offseason for pitching prospect Kade McClure. As Santos thrived in Chicago, McClure, who is more than three years older than Santos, struggled throughout the 2023 season at Triple-A Sacramento.

Berroa actually has a lot in common with Santos. He was also acquired by the Giants in a deadline deal. Originally signed by the Twins, Minnesota traded Berroa, Jaylin Davis, and Shaun Anderson to San Francisco for Sam Dyson at the 2019 MLB trade deadline. Berroa had not pitched outside of short-season ball, but had showcased high-90s velocity and an intriguing breaking ball.

After the pandemic-canceled 2020 minor-league season, Berroa struck out 135 hitters in 98.2 innings pitched with a 3.56 ERA at Single-A in 2021. Berroa did struggle with control, walking 53 hitters over the course of the season. Still, he showcased an impressive ability to maintain upper-90s velocity on his fastball alongside a nasty slider and developing changeup.

Berroa moved up to High-A in 2022, and despite being more than a year younger than the average player in the league, he continued racking up strikeouts and limiting opposing runs. He struck out 16 hitters in 13.1 innings while allowing just one run before the Giants traded him to the Mariners for infielder Donovan Walton, a far older prospect already in the upper minors.

Berroa made 13 more starts with the Mariners' High-A affiliate before he was promoted to Double-A. Over that span, Berroa struck out nearly 40% of the batters he faced and had a 2.41 ERA. His walk rate remained high (14.9%), but was far from enough to overshadow his dominance as a 22-year-old.

At Double-A, Berroa's walk rate spiked even further, driving his ERA up to 4.37. However, he still struck out 53 hitters in 35 innings pitched in the hitter-friendly Texas League.

Berroa returned to Double-A level in 2023, but walked 18.5% of the batters he faced in his first five starts. His struggles with control prompted the Mariners to shift him into the bullpen as a late-inning arm. The decision quickly paid off. 

Following the move, Berroa has a 0.77 ERA and 35 strikeouts in 23.1 innings. More importantly, he saw his walk rate drop to a more manageable 13.5% rate while also earning a couple of saves. His strike-throwing improvements were enough for the Mariners to have him skip Triple-A altogether and head to the majors for a short stint. He did not allow a hit or run across two appearances, striking out three and issuing three walks in 1.2 innings pitched.

As Berroa's prospect stock has continued to rise, Walton's tenure in San Francisco went in the opposite direction. Walton hit just .158/.179/.303 in 78 plate appearances with the Giants and struggled defensively at shortstop. Eventually optioned to Triple-A, Walton has been unable to even produce at league average clip at Sacramento.

The White Sox will hope to replicate with Berroa what they did with Santos a year ago. They also add DeLoach, a 2020 second-round pick who hit .286./.387/.481 with 30 doubles and 23 home runs at Triple-A last season and a compensatory draft pick between the second and third rounds of this summer's draft.

SF Giants president of baseball operations Farhan Zaidi has won plenty of trades since joining the organization. However, Saturday's trade between the White Sox and Mariners reminded him of a pair of deals that he probably wishes he had back.