I agree with IP, that Suns team without Nash, Jrich, or Hedo would have won like 10 games. Look at the defenders Lopez had to work with Vince Carter, Channing Frye, Aaron Brooks, Nash, and Hakim Warrick.
Except he posted the team's worst adjusted plus/minus. The already poor Suns' defense was worse when Lopez was on the floor versus even fringe starters Marcin Gortat or Channing Frye - and Frye isn't lauded for his defense.
Advanced metrics aren't the only measure, but if you can't judge Lopez by his team's defense, and you can't judge him by his individual performance broken down play by play, or by his performance relative to his teammates, how can you judge him? How about the fact that by season's end his coach had given most of his minutes to other players?
Lopez had one good half season stint (the Suns got to the Western Conference Finals without him) in a three year career and has otherwise been a poor defender.
That said, he is Portland's third big man behind Stoudemire and Bogut, he just happens to be one of the poorer third bigs.
And I do like Gerald Henderson's prospects.