Shaw's defense is actually pretty interesting because by the eye test he's pretty stellar, but Statcast hates him.
Fangraphs has two defensive stats: one from Statcast and another called DRS. Statcast is purely automated, while DRS is based on people watching film and grading every play (very very similar to PFF grades in football).
Statcast says he's been 3 runs worse than an average 3B this year, ranking 13th out of 16 qualified 3B. DRS has him at +9 runs, second in the league to only Ke'Bryan Hayes.
Personally, I tend to trust Statcast completely in the outfield, while for infielders I think there's more nuance (tricky bounces, baserunning, etc.) and like to split the difference between Statcast and DRS. That'd put Shaw as a +6 3B. Well above average but not really in the Gold Glove discussion. That lines up with the eye test IMO.