The problem is that there is no evidence to show that Komorov is a good penalty killer, other than his deployment by Babcock.
Furthermore, if Komorov was just limited to 4th line minutes and PK, most would not be in a fuss. But everyone realises that Komorov will be elevated at various points to top lines, that he will play the powerplay, and that he will be on the ice in the final minutes of a game. That is where Komorov truly hurts the team.
What ever line Komorov has played on and what ever line he has been playing against, all stats indicate he spends the majority of his time in the defensive zone, as well has he has some of the worst transitional abilities in the entire league. He has terrible zone entry and zone exits stats, indicating he cannot maintain possession in the other teams zone and has an inability to leave his zone - which means a failure in proper positioning, breakouts, passing and reading plays. Thus when he plays on a top line, he is bringing down that line as a 3 man unit effectively becomes a 2 man unit.
I do not need to discuss him being on the powerplay.
Lastly, when he plays in the final minutes of a game, is where everything about his possession numbers and lack of ability is at it's worst. I've said it previously in this thread, that the NHL is trending in a direction where every player needs to have offensive ability. That does not mean he needs to have a great shot and great passing, but more importantly to be able to read plays, react quickly, and have proper instinct. Komorov defensivly might have effort with his waving of his stick around, yet his pressure is not properly applied, he does not win puck battles, and his inability to understand what another team is doing in their cycle and building their play does not allow him to anticipate to properly defend.
Everything that has happened this season indicates that Komorov is no longer a useful NHL forward. By playing him over other players, you are not icing your best team possible.