Weidman has a much better skills on the feet than Romero and Souza. Romero in order to conserve his gas, is low volume on the feet and usually doesn´t apply a heavy wrestling based game.... but Weidman does. He is high volume on the feet and very offensive with his wrestling. Souza is an expert in bjj, but his wrestling is not on Weidman´s level.
Because of Weidman´s game style, I think he would present a different challenge for Whittaker, and that the fight wouldn´t be as easy as people are saying. I´m not saying he´s better than Romero or Souza, I´m saying he fights differently and would match up better with Whittaker than Romero or Souza imo.