The UFC lightweight division is one of the strongest in the company, it doesn't need any sorting out. You've got Frankie Edgar, Gray Maynard, BJ Penn, Kenny Florian, George Sotiropoulos, Joe Lauzon, Sean Sherk, Evan Dunham, Benson Henderson, Takanori Gomi, Anthony Pettis, Charles Oliveira, Jim Miller, Joe Stevenson, Dustin Hazelett, Jamie Varner, Donald Cerrone, Kurt Pellegrino, Clay Guida, Cole Miller, Ross Pearson, Antonio McKee and Tyson Griffin. That is one seriously stacked division. I love the UFC LW division, and the only guys I'd like to see added would be Gilbert Melendez, Eddie Alvarez, Shinya Aoki and only because I like the dude, Roger Huerta.
My point about sorting out, as in at Middle and Welter, both Silva and GSP need more competition bought in.
At light, Edgar still has Maynard, Henderson (assuming he beats Pettis), Soti and probably Dunham to beat, then perhaps Charles Oliveira down the line. So they don't desperately need either Melendez or Alvarez right now until a dominant champ has been sorted out and needs more competition. I agree, lightweight is the most stacked in the world and in the UFC right now.
They are better going after Lombard and Jacare for an opponent for Silva, nobody is left for GSP after Shields and at light-heavy and heavy, there are still a few decent match-ups to be made, though everybody would love Fedor to be bought in to fight Cain should he get past JDS.