I have the same feeling. While Cain did try to pressure Werdum in this fight, he was too cautious which caused him to play Werdum's game. And at the end he got submitted anyway as well as got really tired. He might have even had an adrenaline dump because he realized that Werdum is beating him everywhere.
Strangely enough Cain needs to be much more aggressive and try constantly to hit Werdum in the face. Hopefully, his cardio will improve (sea level, better preparation, etc). His GnP can work too as long as he does not over-commit and be happy with landing 2-3 punches and restart.
For example, Fedor did escape the first triangle attempt. If he let Werdum stand and try again on feet, the fight might have gone differently. Werdum is certainly a lot better on feet today but he still only punishes fighters who overcommit and forget about positioning. He is no Carwin or Palhares, but is superb at gaining better positioning and taking advantage of it which takes some time. Nelson, Browne, Reem and others did not get finished by fighting somewhat smart.