Lots of potential from these 4 but only one definite starter from the division
Possibly no division in the NFL provides such a diverse amount of opinions on the fantasy potential of the quarterbacks as the NFC West. You can find analysts who love each QB for fantasy purposes and other analysts who don't buy in. Myself? I think there is only one definite starting fantasy QB and the other 3 all have excellent upside, but also have enough questions to make them dicey as more than top potential fantasy backups.
Starter: Carson Palmer
Backup: Drew Stanton
If Palmer truly does still have the arm strength he used to have then he could surprise in 2013 as the Cardinals starting QB. New Cards Coach Bruce Arians has a definite aggressive, vertical offensive style that has proven capable of putting up big numbers from QB's. But I worry that Palmer's arm may not be what is used to and I also question how well an eleven year veteran near the end of his career will hold up if the Cardinals offensive line doesn't show dramatic improvement. But the weapons are there for Palmer to succeed if he can stay upright and show his arm is still able to whip the ball all over the field. A high upside backup fantasy QB in 2013, but also one that comes with considerable risk as well. I was intrigued by Stanton before the Palmer signing as Stanton has a big time arm, but is marked by accuracy issues. Coming from Indianapolis with Arians, at least Stanton knows the system and could surprise with some good games if he was needed, but he could also bomb.
St. Louis Rams
Starter: Sam Bradford
Backup: Austin Davis
While there is a lot of enthusiasm regarding Bradford's new weapons in St. Louis, I think it's unrealistic to expect a major jump up in statistical production. Especially since the Rams lost Steven Jackson in free agency and have no proven rushing attack to support him. I think it may take another year before Bradford starts to become reliable for quality fantasy production on a week to week basis and that's more an indictment of the youth of the weapons he has to throw to more than any lack of talent he possesses himself. One thing Bradford does have is job stability. For 2013, I think of him as being a capable fantasy backup QB with a high upside if his young WR's and new TE gel quicker than I expect. The Rams anointed former undrafted free agent and second year player Austin Davis as the backup to Bradford. While reports on Davis say he looks good, I would seriously worry about his chances to be effective since he has zero regular season game experience. That could explain why they re-signed last season's ineffective backup, Kellen Clemens.
San Francisco 49ers
Starter: Colin Kaepernick
Backup: Colt McCoy
Things were looking a lot better for Kaepernick before Michael Crabtree tore his right Achilles tendon on May 21st. Crabtree and Kaepernick clicked last season when Kaepernick took over and a big 2013 season for both was widely expected. The loss of Crabtree hurts, but Kaepernick proved to be capable as a quarterback and he and his WR's will have plenty of time to get to know each other in training camp. But Kaepernick is also a huge threat rushing as well. In 2012 he was 4th in rushing yards and tied for 3rd in rushing TD's for QB's despite only starting 7 games and not even playing a snap in 3 games. His 181 rushing yards in the playoff game vs. Green Bay were most ever by a QB in a single game. Kaepernick is an exciting young QB who if not for the injury to Crabtree would be in the top 5 of 2013 fantasy football rankings. Even with the loss of Crabtree, imagining Kaepernick with around 3,500 passing yards, 800+ rushing yards, and flirting with close to 30 total TD's isn't that far-fetched. McCoy was acquired from Cleveland to be the new backup and while McCoy is limited as a passer, he could be worth keeping an eye on during preseason in the 49ers offense.
Starter: Russell Wilson
Backup: Tarvaris Jackson, Brady Quinn
Wilson is one of those guys I'm concerned about having a sophomore slump in 2013. I fully expect his passing yardage total to go up in 2013 (he threw for only 3,118 yards in 2012), but after having a 26-10 TD-INT ratio as a rookie, I wonder if he is really going to be everything expected of him after having that type of unexpected success. Also, it remains to be seen if the Seahawks will transition into more of a passing team after their rushing attack has proven so capable of carrying them offensively. But there's no denying that Wilson flashed some skills to be a capable fantasy QB as a rookie. His 489 rushing yards were 3rd best for QB's and that adds value to him. I'd be very uncomfortable with him as a starting fantasy QB, but happy to have his high upside as a backup. Tarvaris Jackson was brought back to compete to be his backup after the Seahawks saw Brady Quinn in the early OTA's. Neither Jackson nor Quinn have successful track records.