From SoxProspects:
Hands work well and footwork is usually reliable. A little stiff and has some trouble getting down on ground balls when charging the ball. Doesn't have great range, but makes up for that somewhat with his length, allowing him to cover more ground than his feet would normally allow. Has made great strides since he joined the Red Sox at third base. Regressed somewhat at third base in 2019 and projects as an average defender there.
He's a strong guy, but his glove work is horrible. Like it says above, he plays very stiff. He doesn't seem to have the quickness to get down on balls. He's terrible at 1b, so I don't know how that'd be better at the hot corner. I don't see how he'd be an upgrade over Devers.