Exactly. Stallone in Rocky - especially Balboa - really is believable and puts alot of heart into it. And he writes them! Hes wrote, produced, directed and was the main character in alot of his films so he's quite obviously talented, especially doing it all at once in some cases. Then people, like you said, see him as oafish because of the muscle and the way he talks..so he does Copland..the complete opposite type of film..and none of his detractors ever mention it lol. That speech in Balboa is amazing advice too.
Arnold is different but if you compare him to a comedian with his timing and delivery of lines, he does an extremely good job. Alot of comedians in films overact aswell..he nails it. He sold it in Twins so well. Plus, in End Of Days he pushed his range and showed he can bring forward more heart. He has always been my favorite actor since childhood, and owning all his films as I do you can see how well hes progressed over the years in acting..he started out sounding like he was reading notes scribbled on his hand and now he delivers each line like its part of him, what more could you ask?
I can't say the same for VanDamme, Segal or Statham. Willis I can, because he can jump from genre to genre with no problem. Not that I dont enjoy those 3 guys films, they just seem one dimensional in comparison to Sly, Arnie and Willis. Alot of actors now dont even look like they are believing what they say..Tatum (I did like him in 21 jump street tho), Taylor Lautner is awful..