To provide some context for what
@LogansDad wrote, Devers by baseball-reference's Offensive WAR was the #15 player in the AL with 4.4, basically equal offensively to Bo Bichette and Luis Robert Jr.
How bad was the rest of his game? He drops down to 3.5 (total) WAR - #29 in the AL (not MLB, mind you, just the AL). Mostly because his defensive WAR is negative. Eyeballing it, it looks like the NL players have 32 players ahead of him per WAR. So call that about 60 players producing more value/wins, with the understanding that WAR is fuzzy. So say Devers is in the 50-70 bracket of players.
But he's going to be paid in the top 10 players in the AL, and top 15 overall. That would make some sort of sense if he was defensively passible, but he's not.
Let's not mince words about how awfully bad he sucked out there in 2023. He was by far the worst regular thirdbaseman by a mile in the AL. I'll define that as someone who starts at least 1/2 of a team's games at 3B (although you can cut that down to 1/3 and the results are still the same.) Pick a metric. Absolute or ratio. He sucked.
https://www.baseball-reference.com/leagues/AL/2023-specialpos_3b-fielding.shtml
The overall effect is that Devers single-glovedly dropped the Sox to the third worst team in the AL at 3B. The only two worse were CWS and OAK.
The next thing we need to note is that this was ongoing. He was slightly better in 2022, when Xander provided some external motivation, and they were both looking for big contracts. The result was he actually clustered with the two other worst full time 3B - Eugenio Suarez and Yandy Diaz.
But go back a year to 2021, and he's the absolute hands-down worst 3B in the AL by a country mile.
https://www.baseball-reference.com/leagues/AL/2021-specialpos_3b-fielding.shtml
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There's one thing Devers can do to really earn his contract, and that's to get better at defense.
Do we hear anything about him hiring a coach or working on his defense? Not really. He may be doing those things. I hope he is, but the posted videos we've seen are of him hitting. And he cannot improve his hitting game enough to earn his contract if he plateaus or backslides on defense.
But it's VERY important that he agrees with some posters here (including myself) that the Sox need established starting pitching.