The easiest thing to do, IMO, is look at the track records of Paul Allen and John Nash.
Paul Allen has a history of listening to the people he's hired to run his basketball team, he has a history of spending a lot of money, and he has a history of winning.
John Nash has a less successful history as an NBA GM. His time with New Jersey and Washington saw his teams firmly cemented in the lottery.
Is it possible Nash is suddenly a great GM and Paul Allen a meddling owner that's screwing everything up? Sure.
I find it more likely, though, that Nash simply isn't that great and that Allen is less willing to make moves that cost him a lot of money and/or deplete the young talent on the roster.
We know that Allen's not entirely averse to spending money (see: Zach and Theo's extensions, Miles's contract, and the reported kibosh on the Penny Hardaway salary dump) and I find it very hard to believe that he's to blame for everything that's gone wrong because he's been ignoring great advice and potential deals from a guy with a history of failure in the NBA.
Ed O.