So many false notions in here.
First is the suggestion that there is a problem with having a coach that wasn’t that good as a player. Look around the NFL and find all the coaches that were outstanding former players. Do you really think that’s the norm? Far and away most never even made it to the NFL at all, and they were never remotely close to even the college player Kellen Moore was. Of course, if you want a quality former player coaching, Colombo fits that criteria, but you don’t like him either.
Second, all of us did not think of Moore as a joke at QB coach. Most had some concerns about his lack of experience, and I did as well, but ultimately QB coach is not a top level coaching position, and Moore is highly thought of by everyone that has ever played with him or coached him, so I was willing to take a wait and see approach.
As for Kellen Moore becoming OC, the one reasonable concern is his lack of experience. Not how well he did as a player - by that criteria he would be an elite candidate for OC compared to other NFL OCs. As for Colombo, everything I’ve read and heard indicate the O-Line took a turn for the better once Alexander got canned and Colombo took over.