I don't believe that recognizing poor coaching and desiring improvement is inconsistent with being a fan. On the contrary, I believe that a fan should want the coach and the program to improve and may (not must, but may) make that desire known. This does not include booing the players. The players are college kids, and not adults or professional athletes, and should be treated as such. That may be a quaint or naive notion, but I have lots of gray hair and tend to be a little quaint and naive.
I also don't believe that expressing frustration is inconsistent with being a fan. A fan can be honest. Saying that something is good when it isn't shouldn't mean that one is not a fan.
I believe that a coaching change is necessary, but I will be cheering for the team to win for the rest of this season, and for the seasons to come.