The biggest difference which led to Weidman connecting was his fearlessness to lean in and go for the hook. Everyone else was too scared, thinking they'd get suckered in, so they stayed back and jabbed away, which left'em open for Spider to quickly go into attack mode and catch'em.
Early on, he was doing the same shit with Weidman and caught him and a few times...go into the second round, and Weidman just leaned in, full bore, and caught'em clean on the chin and considering Silva was already trying to matrix he was done-zo. Eyes rolled back like an antique cash register. Would not shock me if that was a plan going in...let Spider clown, but don't be scared to be suckered. The two dudes with the most success against Silva...Weidman and Sonnen I, went in fearless.