Do we even know what really happened between the two? I heard Andy got rid of him as he was too annoying. Some said Andy had to get rid of him to go his own way. I dislike Brad a lot. He seems to hate anyone who wins without real struggle. But if you are grinding it out and winning each match after 5 hours, you are Brad's hero?
What happened, from what we can tell, from what Andy had ghostwritten for him in his book, was that spending too much time in close quarters with just him and Brad was too overpowering a personality. Andy also felt that Brad just didn't get him as a player, always demanding he play more aggressively even when Andy felt the right tactics were to be more consistent. I think the wrist injury he suffered in Hamburg in 07 when Brad told him to play on and didn't seem to realise how serious it was, caused quite a major breach.
They didn't seem to communicate well either - Andy wrote that sometimes after tournaments when Andy had lost, he'd find a note under his hotel room door from Brad about what he thought, and Brad would already be on a flight to somewhere else.
I think there was just a generation gap and clash of strong personalities, but the terse and disdainful way Murray ended the relationship, not even speaking to Brad personally, and the very pointedly unenthusiastic statement Andy's team put out to the press with the announcement was not well handled at all.