Shelden is supposed to be Powe's replacement but he's is awful. They signed him to a one year deal for 825K, and the Cavs signed Powe for a two year deal with approximately the same annual value. I'd much rather have Powe in limited minutes.
No, Sheed is the replacement for Leon Powe. Who wants to take back Powe instead of Wallace? Shelden is the replacement for Patrick O'Bryant, another disappointing big man taken with a high draft pick who has enough talent to be a reasonable gamble for a minimum contract.
I dare anyone to make the case that Shelden Williams is not an upgrade over POB.