I'm just really confused about what's bad enough where you get to dress... but you don't get to start... but you do get to play... but not much.
I tend to agree with LAX and others that it's a (questionable) coaching decision.
But to play devil's advocate, and to cite an example that worries me in terms of Redfield for some reason being in BK's doghouse, I'll cite Marcus Barnett, a receiver during BK's time at UC.
Here are his stat lines from 2007-2009, the three years BK was at UC:
2007 - 62 rec - 862 yards - 13 TD's
2008 - 30 rec - 277 yards - 1 TD
2009 - 10 rec - 95 yards - 1 TD
As a true freshman in 2007, as part of a veteran and very nice receiving corps, he killed it, and looked like another great to line up alongside Mardy Gilyard. Those are incredible numbers for a freshman.
However, as a sophomore and junior, he basically disappeared. He dressed and played sparingly, just as we are seeing with Redfield now, but never climbed out of the hole he was in. There was never any reason given, and BK always talked positively about him when asked about the situation, but it was clear from people close to and within the program that Barnett had done something that irritated BK. Even though he was maybe the second best receiver on the team as a sophomore and junior, he didn't play much.
So, whatever he did was just like what you referenced with Redfield. He did something, but it wasn't bad enough to keep him from dressing, and he played, but only a little bit.
Again, just playing devil's advocate. Redfield obviously didn't make a Barnett-like impact before getting this bench treatment, but the sudden and confusing decline is similar to what I witnessed back in BK's time at UC, which worries me.