I think its far too late to fundamentally change him, but just show him a few more things to mix it up. He can't be just moving forward with his guard up and lunge in the whole fight at this weight and at this level. He's gotta have a few more options than that to hope to be competitive.
AA is possibly the biggest fighter at 160 that i can remember, he might of outgrown the weight now he is campaigning at 168lbs. The guy has power but thats about it, any guy with decent lateral movement, that is willing to use angles will have success against the current version of AA. so a new trainer is not a bad idea in my opinion.
don't be so sure about this weight thing. the whole "aa too big for mw" was, in reality, a marketing ploy by his people to make him a viable part of the S6 tourney. think about who his promoter is and what part his promoter played in putting this thing together. just like a dibella fighter (taylor) goes out and another dibella fighter (green) gets insterted. the S6 required serious marketing. i'm glad they did it and i'm glad aa was a part of it. but the fact that he himself said he needs to go back to mw is very telling. still, the fact that he got in there w/ taylor, dirrell and froch means a tip of the hat to him. nevertheless, he is a mw by his own admission. aa can make some noise at mw.
Lujaun Simon is a broke-dick, poverty-stricken version of a poor mans drunk Kelly Pavlik. AA isn't making any noise in any division against any world class fighter. He's been exposed for what he always was, and can never be un-exposed.