The San Francisco Giants got the offseason started in earnest on Thursday, when they got in on the flurry of minor moves flying around Major League Baseball. The Giants, after declining Tom Murphy’s option,
had one opening on their 40-man roster, meaning they could add one player without having to make any corresponding moves.
Instead, they added two players, and a corresponding move was necessary. And so on Thursday afternoon they designated right-handed pitcher Mason Black for assignment, while claiming left-handed pitcher Reiver Sanmartin and outfielder Justin Dean off of waivers. The Giants announced the move on social media, after sharing a press release with reporters.
Dean, a right-handed hitter who is about to turn 29, comes to the Giants after being DFA’d by, you guessed it, the Dodgers. A 17th-round pick by the Atlanta Braves back in 2018, Dean spent the majority of the 2025 season with LA’s AAA affiliate, where he hit .289/.378/.431 (110 wRC+), with six home runs in 347 plate appearances. He’s a small ball player: he doesn’t hit the ball hard, but had a great average last year, perennially has a walk rate in the double-digits, plays strong defense, and has stolen 89 bases over the last two years. He made his MLB debut this year as a late-inning defensive replacement and baserunner: he appeared in 18 games, but had just two plate appearances. He has three Minor League options remaining.
Sanmartin is a 29-year old who comes to the Giants from the Reds, where he made his MLB debut in 2021 and has appeared in each season since, though 2022 was the only year where he had a stable role. He’s struggled to this point in his career, posting a 5.66 ERA and a 4.45 FIP in 62 appearances, with 73 strikeouts against 42 walks in 84.1 innings. He only appeared in one Major League game this year, but had a 2.67 ERA and a 3.81 FIP in 67.1 innings for their AAA affiliate. He has a four-pitch mix — four-seam, sinker, slider, and changeup — though he doesn’t pitch with much velocity. He has one Minor League options remaining.
As for Black, the writing was on the wall after a very rough 2025. The third-round pick in the 2021 draft had a 5.81 ERA and a 5.64 FIP in AAA this year, and made just one appearance in the Majors after the team exhausted virtually every option before turning to him. With a Minor League option remaining, there’s a decent chance that Black will get claimed, but if not, the Giants can keep him in the system by outrighting him to AAA Sacramento.
