The biggest difference between the "good" Savage raiders and the "bad" casuals struggling through Normal has nothing to do with skill and has everything to do with tolerance for failure.

The #1 most important skill someone needs to kill Savage bosses is the ability to make a mistake, dust themselves off, and try again.
(Tied for #1 is the ability to handle it maturely when someone else makes a mistake)

A huge chunk of the people who feel like they're struggling with the new content and feel like it's too hard are performing better than a lot of the more hardcore players around them. The only difference is that the hardcore players are taking their own mistakes in stride because they know mistakes are inevitable for every player.