They HAVE. You probably just didn’t pay attention when they were pointing out Leinart’s problems, or Vince Young’s, Cam Newton generated a lot of bad press this year (second season), Jay Cutler generates so much bad press you’d think he owns stock in an ink company.
Bad press is everywhere in the NFL. Most of the time a player is discussed by name it’s pointing out his faults. There’s a handful of media darlings like Peyton and Brady, but everybody else gets criticized. And even the darlings get hammered sometimes, Peyton got a lot of bad press during 2011 for negotiating a big contract extension BEFORE getting his neck surgery.
Which basically proves my point - I don't hear anything about those other names you mention, yet read about Tebow and his "mechanics" all of the time.