Because his cardio and stand-up (aside from kicks) sucks?
Wow were to start. First off Gonzaga doesn't have shitty standup, just because it looked bad in the Werdum fight. rewatch the Randy and Cro Cop fight, his punches look very crisp when he gets to use them. The Werdum fight is an anomoly to me, because I have never seen anyone gass in 1 round (and FTR he was easily winning that fight till he gassesd). Oh and just to avoid future argument on that comment, yes he gassed he didn't get rocked. I remember telling my friend about 30 seconds into the second round (far before Werdum hit him) that Gonzaga is completely gassed.
Gonzaga would be a future champ if it wasn't for Nog, and even then I sometimes think he can beat Nog. Plus he is still young and is always improving. And so what if he got subbed my Jacare, Jarace is the only person I can remember ever subbing Marcelo Garcia (the best BJJ artist in the world except for maybe Rickson). Everyone gets subbed by Jarace at some point.
Also, you neglect the fact that Gonzaga has top 5 wrestling/tdd in the UFC HW division, an incredible chin, KO power in his hands, and the strongest kicks in all MMA. He will be the future of the HW division if he gets his cardio and head together (and if he looks anything like the McCully fight next fight then that will be a great start.)
Also people are severly overrating Anderson's BJJ, Blackbelts have their gaurds passed all the time, and while Silva does have very good BJJ, Gonzaga is about 2 leagues above Anderson in that level technically, not to mention strength wise.