A Tier 1 quarterback can carry his team each week. The team wins because of him. He expertly handles pure passing situations.
Tier 1: Rodgers, Brady, Brees, Roethlisberger
A Tier 2 quarterback can carry his team sometimes, but not as consistently. He can handle pure passing situations in doses and/or possesses other dimensions that are special enough to elevate him above Tier 3. He has a hole or two in his game.
Tier 2: Ryan, Wilson, Stafford, Rivers, Wentz, Luck, Newton, Carr, Garoppolo, Watson
A Tier 3 quarterback is a legitimate starter, but needs a heavier running game and/or defense to win. A lower-volume passing offense makes his job easier.
Tier 3: Cousins, Smith, Manning, Prescott, Goff, Winston, Mariota, Dalton, Flacco, Keenum, Taylor, Bortles, Tannehill, Bradford
A Tier 4 quarterback could be an unproven player with some upside, or a veteran who is ultimately best suited as a backup.
Tier 4: Trubisky, McCown, Mahomes, McCarron