Meh. Great numbers in extreme sheltering.
Only 1 year he's had non-buttersoft minutes was 18-19. Spot the outlier:
17-18: +.18xgfrel (-4.9qoc)
18-19: -.19xgfrel (+1.7qoc)
19-20: +.33xgfrel (-20.9qoc)
Boston may be making a mistake this year not realizing how crucial Chara taking the most extreme minutes in the league was for the rest of the defense.