In fairness I can confidently say as a Pens fan that Letang's brain has always been swiss cheese. I love the guy and he was a hell of a player in his prime and he always plays at max effort but he's always had severe brain lapses on the ice.
As for EK, I was disappointed that he sucked on the PP. His 5v5 play was pretty good still despite the decreased production. He made a few too many boneheaded turnovers and I'd like to see him cut those down a bit but honestly our d was wayyyyy better off with him than it would have been with Rutta/Petry. (not that that's a high bar to clear)
I think EK suffered this year from the same shit Letang used to which is people laser in on the turnovers and forget the other 95% of the game where they're helping the team on the ice. The blunders are infuriating but you take the good with the bad when it comes to guys like EK/Tanger.