This guy has an interesting analysis - the 'Ron' of the Films was different from the 'Ron' of the books because his cool moments were stripped from him and given to Hermione:
"During The Prisoner of Azkaban, Sirius Black is trying to get to Peter Pettigrew (currently disguised as Scabbers the Rat), but Ron and Hermione are convinced he’s after Harry. In the book, Ron stares up defiantly from his mangled, broken leg and tells Sirius Black that if he wants Harry, he’ll have to get through his friends first.
And in the film, it’s Hermione who boldly steps in the line of fire while Ron sobs in pain and babbles incoherently.
These rewrites not only depict Ron as an idiot coward—they also make him an outright jerk."
http://www.tor.com/blogs/2014/01/erased-...on-weasley
"During The Prisoner of Azkaban, Sirius Black is trying to get to Peter Pettigrew (currently disguised as Scabbers the Rat), but Ron and Hermione are convinced he’s after Harry. In the book, Ron stares up defiantly from his mangled, broken leg and tells Sirius Black that if he wants Harry, he’ll have to get through his friends first.
And in the film, it’s Hermione who boldly steps in the line of fire while Ron sobs in pain and babbles incoherently.
These rewrites not only depict Ron as an idiot coward—they also make him an outright jerk."
http://www.tor.com/blogs/2014/01/erased-...on-weasley