I agree that Simms may not be quite ready to be exposed to premier football yet. His all round game is improving though and was the first thing I noticed in the couple of games we've seen him this season.
However I have to disagree on your opinion that he doesn't fit the counter attacking profile that Ancelotti is looking for. The lad is deceptively quick, has a great turn of pace, is very comfortable playing on the shoulder of the last defender and, probably most importantly, is clinical in one on one situations. He rarely misses the target and if he doesn't score he invariably ensures the keeper has to make a save.
If he continues to improve over the next couple of years he could fit perfectly into a counter attacking system. Maybe I'm doing the lad a disservice by saying he isn't ready and perhaps Kean going on loan may open a door for him.