This stuff is a bit crazy guys. McCall made a lot of good moves last year (and I'm no apologist of his, I've posted endlessly in years past about my gripes with the offense).
The play calling in a large number of games in 2018 was absolutely solid; we aired it out when CT was on his game, we shifted to having Bowser carry the work load when CT was struggling. The 2nd half adjustments against Ohio State and Utah were good and got the offense moving the ball down the field well.
Our offense went through 2 or 3 transformations last year (losing Larkin as CT recovered, CT going through ups and downs at times, Bowser's emergence), and we won 8 Big Ten games and a bowl game. There are not many offensive coordinators who could manage that as well as McCall did.
That doesn't mean that McCall gets a pass for this year, but it does mean that I'm going to give him time to see what the offense can do this year and early next season. What we're seeing right now is the baseline and there has to be improvement. But we just won 36 games over 4 years including 3 straight bowls and a division title. There's no need for rash moves when we already have a new OL coach and a new QB.