Hernanes' problem is that he has two feet he can pass and shoot with but not one that could trap a bag of sand. That stalls momentum when constructing attacks, that extra second controlling the ball.
These are all small details though. I'm pretty sure we have these spells every season, you see us gradually get worse and worse until we lose, then we reel off a bunch of wins, we slack off again trying to balance out the fixture list, we stumble along again, then tend to fire towards the end of the season. Same shit all the time. It's all about desire. Putting it together for a one off game is one thing, no team can have it for an entire season when you have European football. We just seem to get into a malaise for a string of games before something really kicks us up the ass. I'd imagine that while we are still top you won't see something startling from us.
I could understand it more if we looked like we were really going for it in the CL, but that doesn't seem to be the case.