Styles make fights. Vitor can look awesome knocking out everyone standing not named Anderson Silva, but put him back in there against the greatest striker in MMA history and he will get his head punted off in short order again.
Weidman on the other hand can look less impressive beating others with his wrestling, but he has a high chance of doing the same to Anderson, from what we've seen of Anderson in the past and Weidman's sub defense.
You are being biased in saying Weidman has only "decision-ed Maia" as if that's all he's done. He is 5-0 in the UFC, 9-0 overall, most of his other fights have been finishes and believe it or not Munoz was also on a tear and ranked top 5 when Weidman demolished him. He is undefeated, has shown no vulnerability, and hasn't yet fought or lost to Anderson. None of these things Vitor has on his side, who has never shown heart going past the first round. When Vitor's good he looks fantastic. When things don't go his way, he looks like crap. Selective highlighting can make anyone look better than anyone.
Sonnen is better at everything Weidman is good at? How about sub-defense? Does Weidman get triangled every third fight? Do you know what Sonnen + Sub defense in the first Anderson fight would mean? Champion.
And believe it or not, Weidman is a better wrestler than Sonnen. Sonnen has never beaten another top wrestler, in fact he just got tooled by one in the wrestling department, albeit a bigger one. Weidman has, in Munoz, an NCAA div-I champ. Even credentials wise, Sonnen may have been an Olympic benchwarmer but at the NCAA div-I level Weidman finished 3rd at his best while Sonnen finished 8th.
Lastly, even striking wise Weidman is better. That standing elbow on Munoz was timed so perfectly, and his striking has looked crisp in all his fights. Aside from a flukey knockdown on an injured Anderson (which was more an off-balance thing than a dazed knockdown), what has Sonnen ever accomplished striking in his entire 40 fight career? Absolutely nothing. Name one other KO, knockdown or even "rocking" someone he has had standing.
I think a more accurate statement would be Weidman is better at everything than Sonnen.