In response to TripleOG's comment:
Thats a nice point to make and it may hold some weight but you see the problem is Dane Fletcher, you know the undrafted guy and Spikes, the guy noone wants resigned seem to be doing an ok job with the same guys in front of them. How do you explain away Fletch and Spikes making multiple stops in the backfield against the Broncos while Hightower was being pushed 5-7 yards back and making tackles almost 10 yards downfield. So yes our tackles are not great but hightower would look bad behind Ted Washington, Ngata and Wilfork in a 34 defense. He is un enthused, no sense of urgency and instincts are not even close to what it should be for an inside player.
If Hightower had the luxury to man the middle on two downs like Spikes does than he would lead us in tackles, as it were he currently is third on the team and led the team in tackles against the Texans last game. He led us in tackles (10) against the Dolphins also recording 2 tackles for loss and a sack.
He is being asked to play out of position because, as much as you'd like them to Dane Fletcher and Jamie Collins can't play every down at the "mike" linebacker position, so when your only other option out there is Spikes, you go with Hightower.
Can you imagine Spikes out there trying to man cover anyone? You don't have to because it will never happen, but unfortunately for Donte he and Spikes play the same position and Spikes is so limited the team has no choice.
Injuries have this effect on teams, we had the best defense in the NFL for the first 1/4 of the season and nobody was complaining, now we lose two team captains in Wilfork and Mayo along with our other starting defensive tackle in Kelly and suddenly everyone "sux."
It couldn't be complementary football breaking down, it couldn't be players like Hightower and Arrington being asked to step outside their comfort zone... again, learn the game.