Hobbs has been taking some chances returning kicks that are kicked deep. Because of his ability he has gotten away with it, like he did on that 108 yard return against the Jets.
However, against Cincy he took 4 kicks out of the endzone and he only reached the 15 and 21 on 2 of them. Then his first return against Cleveland last week wasn't a great one (an 18 yard return to the 20 where he looked like he danced a little instead of just taking what was there). After that Welker replaced him.
I think the coaches are just sending him a message to be smarter. The 108-yard return was great, but there is no shame in taking a touchback in a ball kicked deep, you don't have to bring everything out. Also, he can't show hesitancy looking to break the big one, he has to hit it up there and take what is available. Welker does that.
I just think they are sending a message. It wouldn't surprise me if he is back there this week.