I think Sarvre is in a "damned if you, damned if you don't" situation.
First, he fails to sign JJ when he was cheap but not clearly an elite player. That blows up.
Second he signs Diaw for more than he's worth to avoid a repeat of the JJ fiasco.
The Suns tried to jump the team into the elite by signing free agents. Home run with Nash, but foul out with Q Richardson (can you image what it would cost unload him now?) and an apparent strike out with Banks. Jones was a neutral signing but too expensive for a team in the LT region.
Oddly enough, the biggest blunder was clearly not Sarver's fault. BC traded out of the 2004 draft in order to get cap space but then could not get what the second guy he was hoping for and settled for Q. In retrospect, it turned out to be a disasterous decision.
With 20-20 hindsight it is easy to say they messed up. Still, they've done enough things right to have an elite team. It's just frustating that they just don't seem to have the kind of Omniscience that we all possess.