Guys, like I said ID'ing the Mike isn't the point. That's easy for any quarterback to do. How you ID the Mike doesn't change whether it's NFL, college or high school.
Don't get focused on that part.
What they're trying to get Rosen to understand are the responsibilities of the other defenders and where the windows are going to be based on his pre snap read. What the options are going to be. But he has to master the protections first by ID'ing the Mike. Then they'll try to get him to understand who the flat defender is based on where the apex linebackers are - and whether or not this guy is responsible for carrying the wheel route first and rallying to the flat, etc. Then whether or not the MOF is going to be closed or open.
Just from reading others observations of what's been going on with him in practice, I believe understanding where the windows are going to be and understanding which defenders are responsible for what are things he hadn't learned yet, and why he was throwing some picks and attempting throws into windows that aren't designed to be there as options. Checking it down is showing that he's beginning to understand where the windows are NOT going to be.
The defense is going to tell you where to go with the football once you understand where the windows are going to be. They're teaching him how to read defenses, and make him understand that the QB is going to be responsible for the protections in this offense. Which is the first thing he has to master in order for them to put him out there. Then the curl/flat - then the MOF - so on and so forth.
The deep shots are going to come last. Fitzpatrick is further along and quicker at identifying whether or not the MOF is open or closed, which is why he takes more deep shots. It's a process. They're bringing him along like a rookie.