Pierce is a better player than Gay on a great contract. This means they have to trade more talent than Boston does to make this trade work.
Not sure if this is true. I think Pierce having a good contract is offset by Gay being in his prime. If Gay's contract was exactly the same as Pierce's you would have to say a 27 year old Gay is a more valuable asset than a 35 year old Pierce given their currents stats. Pierce is more efficient but he's also more likely to drop off or be injured. Gay is less likely to do those things so soon.
The reason Memphis is an ideal partner is that they would value Pierce's cap relief and his production for the rest of the year. We don't have the same value for cap relief because even without Pierce's contract we still exceed the salary cap, though we do get our of paying some taxes I believe. Being over the cap means we couldn't add a big contract even if we didn't pick up his option next year.
I'd like Gay and Wroten for Pierce. I'd take just Gay though.