On Friday night against the Tampa Bay Buccaneers it was Kansas City Chiefs offensive coordinator Bill Muir calling the plays in the 25-0 shutout. The Chiefs starting quarterback was in there for eight plays and didn't pass once and that was probably by design.
The Chiefs lost big but, as Todd Haley points out, the nature of the game makes it hard to evaluate Muir's playcalling duties. Via KCChiefs.com:
"You know, I think that going back to this idea of us being focused on ourselves, we were so simplified in so many areas across the offense, defense and special teams really that I'm not worrying about that being too good of a grade or too poor of a grade one way or the other. It was just such a very limited package that it really was about as simple as you could be. I still don't think we're really at the point to worry a whole bunch about that."
So we're no closer to figuring out who will call the plays but from a continuity standpoint I would think the edge goes to the guy who calls plays in the preseason which would be Muir. On the other hand, Haley's going to be lurking there this offseason so it's just as possible he's calling plays.
Unfortunately, preseason is such a small sample size and experimental time that I don't think we'll be able to accurately judge Muir's ability to call plays in these four games.