Each rating compares him only with players who take that role, so the four are not measured against the same field.
Even-strength offense1533 min87among all skaters at the position
Even-strength defense1533 min56among all skaters at the position
Power play76 min74among defencemen who run a power play · small sample
Penalty kill145 min27among defencemen who kill penalties
Season by season
Every season is drawn on the same scale, so bar length is comparable top to bottom. Bars left of the center line cost the team goals; bars right of it earned them.
A player's rating is his percentile among NHL defencemen — a 70 means he is better than 70% of them. It is measured from wins above replacement, the number of wins he adds compared with a player freely available to any team. See the full roster table or read how this is calculated.