Miller and Lord were stunned to find that they were not being granted freedom to run the production in the manner that they were accustomed to.
Freedom is not something anyone should expect running a big movie. Because they're not running it, the studio is.
Michael Bay has enough experience that (god help us all) he can probably get his way nine times out of ten, but when it's your first big studio film, they are the boss. If you can't find the point where you're ideas mesh with theirs then it's not going to work.
It's just a damn shame they didn't all realise this in pre-production.
As for Howard; he's made some movies that didn't work for me but for Disney he's an experienced hand, has made huge films in the past and is one of the nicest guys in Hollywood. Even Russell Crowe could;t find a way to get into a fight with him.
At this stage he's just what Disney would like to be dealing with.