Each rating compares him only with players who take that role, so the four are not measured against the same field.
Even-strength offense614 min24among all skaters at the position
Even-strength defense614 min26among all skaters at the position
Power playDoesn't play on the power play
Penalty kill116 min34among 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.