I disagree.
Every offseason, we can make a list like this of signings that surprise us, which could easily lead to the conclusion that market value is higher than we think it is. Then 2 years later, the teams that make those signings all find themselves hampered by them and then are desperately trying to trade them away.
I remember very clearly people on this blog discussing that Rudy Gay, Joe Johnson, Josh Smith, Eric Gordon, Tyreke Evans, John Salmons, Perkins, Villanueva, etc. all were overpaid at the times of their signings. Every offseason, we celticbloggers can't count on 10 fingers how many of contracts like that get issued. It doesn't mean we're wrong on our perception of what market value is.... it means the GMs are wrong about what their perception of market value is.
I mean, isn't it interesting that the Spurs never seem to find themselves with those players? Teams like Phoenix and Houston have done fairly well lately in that regard as well.