The Giants cashed in a reliever for a former top prospect in one of the biggest surprises of the deadline. San Francisco acquired infielder Marcelo Mayer from the Red Sox for lefty Erik Miller and outfield prospect Carlos Gutierrez.
Boston moves on from the 23-year-old Mayer, the fourth overall pick in 2021. The lefty-hitting infielder was viewed as the Sox’ shortstop of the future at the time but didn’t pan out with his original organization. While some of that was injury related, Mayer also hasn’t produced in his big league opportunities over the last two seasons.
The Sox initially called Mayer up as a fill-in third baseman while Alex Bregman was injured last summer. The youngster appeared in 44 games and hit .228/.272/.402 before suffering a season-ending right wrist injury. He underwent arthroscopic surgery in August. Boston acquired Caleb Durbin from the Brewers last winter, pushing Mayer to second base.
That also hasn’t gone as planned. Mayer has taken 228 plate appearances in his first full big league season. He’s hitting .220/.282/.312 with three home runs and stolen bases apiece. Mayer has made some modest improvements to his contact ability relative to his rookie year, but he hasn’t hit the ball with any kind of authority. He’s averaging a paltry 86 mph off the bat and has made hard contact just 35% of the time. He went on the injured list in late June with a stress reaction in his left forearm and will begin his Giants’ tenure on the IL.
Mayer clearly hasn’t found his stride to this point, but it’s easy to see the appeal for the Giants. He’s only a couple seasons removed from being one of the 20 best prospects in the game. Mayer has hit .274/.360/.466 over his minor league career, and he did make a lot more hard contact before the wrist injury as a rookie. Though he was never the flashiest prospect in terms of physical tools, most scouts felt he was a polished enough hitter with solid defensive actions to fit in the middle infield.
San Francisco traded Luis Arraez to Philadelphia, so they can give Mayer a look at second base once he’s healthy. They could try to move him to shortstop or third base if they’re able to find a taker for either of Willy Adames or Matt Chapman in the future. Mayer still has a full slate of minor league options and only passed the one-year service mark this season. The Giants have him under club control for at least five years, assuming no changes to the service time setup in the next CBA.
It’s clearly a disappointing outcome for the Red Sox given Mayer’s draft pedigree. They made that selection under the previous front office. It seems chief baseball officer Craig Breslow and his staff weren’t wedded to Mayer as a franchise building block. He’d clearly been surpassed by Franklin Arias as the team’s shortstop of the future. While they could have kept Mayer at second base, the writing seemed on the wall after Boston traded a talented rookie pitcher (Connelly Early) to acquire Curtis Mead to play second. The Sox still have Trevor Story signed through 2027 as well.
Miller is a talented but enigmatic left-hander who can compete for a late-inning role. The Stanford product has pitched parts of three big league seasons, all with the Giants. He missed the second half of last year with an elbow sprain and had a brief injured list stay due to a lower back strain this May. Miller has shown big swing-and-miss stuff when healthy, pitching his way to the back of the Giants’ bullpen.
The 28-year-old southpaw has picked up four saves as part of a closer committee and has another 10 holds in 38 appearances on the year. He carries a 2.76 earned run average over 32 2/3 innings. Miller has punched out an excellent 32% of batters faced and has a near-54% grounder rate, but he has walked nearly 16% of opponents.
That’s typical production for Miller. Few pitchers can match his combination of swing-and-miss and grounder abilities, but he has the second-highest walk rate among pitchers with 80+ innings over the last three seasons. He works mostly with a sinker-slider mix, averaging 97 mph on the fastball with a huge whiff rate on the slider. That arsenal is particularly tough on left-handed batters. Righties haven’t done much damage against Miller either but have drawn enough walks to reach base at a .375 clip.
Miller joins Jovani Moran as lefty setup arms in front of Aroldis Chapman. He entered the season with exactly two years of service time and will quality for arbitration for the first time this offseason. Miller is under club control for three and a half seasons. He also has a full slate of options, though the Sox are surely hoping he’ll be too valuable a bullpen piece to send back to Triple-A.
Gutierrez is an odd inclusion but clearly a player whom Boston scouts and/or analysts identified as one they like. He’s a 21-year-old left field prospect (22 later this month) who is playing in High-A. The lefty-hitting Gutierrez has a .271/.385/.441 line with nine home runs and 26 stolen bases in 28 tries. He’s walking at a robust 15.1% clip against a manageable 20% strikeout rate.
Brendan Gawlowski of FanGraphs ranked Gutierrez the #33 prospect in the Giants’ system. Baseball America had him 24th in the organization. The 5’10” Gutierrez is an advanced pure hitter but doesn’t have huge physical tools. He’s not expected to grow into much power and is an average runner. There’s a decent chance he ends up with a tweener fourth outfield profile as a result, but the Sox clearly believe in the bat enough to take a flier.
Ken Rosenthal and Andrew Baggarly of The Athletic first reported the Giants and Red Sox were nearing a Miller/Mayer swap. Respective images courtesy of Kevin Ng/Denis Poroy, Imagn Images.
