The last two games have been rough defensively, but most of the season he's played pretty clean. Tonight the big defensive miscue was more a miscommunication with Jarry - or thinking a forward was coming down the wall. There were a few rough plays with the puck but he wasn't alone in that, certainly. I think on the whole at 5v5 he and Letang have had similar amounts of screwups with the puck. Letang has been great on the PK but I've seen him screw up plenty defensively. Even Pettersson isn't playing the way he was the first half of the year.
Most of the season EK has done pretty well in the Sullivan system, even though it has limited his breakout game severely. I've watched EK his whole career, he's done a lot of things well defensively this year that he hasn't always done - but whereas in his prime in Ottawa he would make a nice play and then bomb up ice with the puck to start a rush, here he'll gather the puck and fire it to the centre line, or just send it over to his partner. However much he may want to get up ice, he's done what Sullivan has wanted all season.