I have to disagree with you. I think rebuilding is a bit of a cliche anymore. It will take time for the players to adjust to new coaches and scheme. I don't think this team needs rebuilt from the ground up. It's just impossible to do anymore. If these coaches want to be employed from more than a year or two they are going to have to coach up some players. There is a lot of untapped potential on the roster and there are a few that will never reach that potential. Maybe 2017 for legit super bowl contention if things are going well but the team should be competing for a playoff spot in 2016. You may be right on not contending in 2015 but I wouldn't be that surprised if they did.
For the defense, the only constant was that everyone looked bad. Tucker ran a poor scheme, didn't develop hardly any talent and was undisciplined. There has been one player on the D that has shown any kind of progression and development and that's Paea. There are guys on the roster that aren't even close to reaching their potential. There is a lot of evaluation left to do on this defense. This year the players should be put in the best possible position to succeed and then they can truly be evaluated. I wouldn't be surprised to find 5-6 guys currently on the roster to emerge as quality starters.
For the offense, we all know the story with Cutler. We all also seem to look past how long ago he took the bears to the NFC championship game with nobody at WR. Cutler sure as hell isn't the answer, but it is possible to win with him. Pieces are in place on the offense to put up enough points to win every single week. They were the #2 offense in 2013. Add a starting right tackle and a speed element at WR and there is no reason this offense shouldn't score at least 20 points ever week. You can win with that in the NFL.