Passing efficiency is a nice stat for comparing quarterbacks. It's not perfect for a number of reasons, not the least of which being that it doesn't account for mobile quarterbacks' rushing, but it does a fairly good job for what it's intended to do.
An outstanding season passing efficiency score is 160 or above. Some years don't even have a single player reach that level. The majority of players who do hit 160 or above are either seniors or upperclassmen who leave for the pros early. Since 2000, when the NCAA stats archive begins, only 24 players have hit 160 passing efficiency and returned the following year.
I cataloged 21 of those players last offseason, so hit this link if you want to see them all. The missing players didn't play enough games the following year to count in the NCAA's season standings. Three of the 21 improved their passing efficiency scores noticeably, two of them posted basically the same rating as the year before, and 11 posted noticeably worse passing efficiency. Two more had done it in 2010 and couldn't be measured yet: Andrew Luck and Kellen Moore.
Luck's 2010 passing efficiency was 170.16, and it was 169.69 in 2011. His basically stayed the same. Moore's was 182.63 in 2010, and it fell to 175.19 in 2011. He had a chance of maintaining or improving, as he was one of the three to improve after posting a 160+ passing efficiency after putting up 161.65 as a sophomore, but his declined. He did join Tim Tebow as one of only two quarterbacks to officially post a 160+ passing efficiency in three consecutive seasons since 2000. Moore did not, however, buck the trend of every junior on the list posting a lower passing efficiency mark as a senior.
Last offseason I suggested that Luck and Moore would have difficulty winning the Heisman because of this trend. History indicated that both players would see their passing efficiency scores either remain the same, or, more likely, fall. That wouldn't preclude them from winning it, but players rarely win the Heisman without a noticeably improved statistical season than what they've posted in the past.
Robert Griffin ended up winning the Heisman by a comfortable margin over the second-place Luck largely because he played one of the best seasons a college quarterback has ever had. And while elevating historical doormat Baylor to nine wins had a lot to do with his winning the award, it also somewhat had to do with Luck not surpassing his past performance. Luck was spectacular, but he didn't outshine his own previous season much less Griffin's stellar year.
Three quarterbacks from 2011 posted a 160+ passing efficiency and are coming back. One of them you've definitely heard of: USC's Matt Barkley (161.22). One of them you will have heard of if you're a big college football fan: Washington's Keith Price (161.93). The third one I doubt you'll have heard of because I didn't know the guy either: Toledo's Terrance Owens (169.24).
Of them, the rising senior Barkley is the strongest Heisman candidate. He finished sixth in the 2011 voting even. Before you pencil him in the 2012 winner's slot, keep in mind that no junior since 2000 who has posted passing efficiency of 160+ has beaten that mark as a senior. It's a fairly safe bet that his passing efficiency performance in 2012 will be equal to or slightly below his 2011 level. That means Barkley probably won't win the Heisman unless his team is headed to the national title game.
Price will only be a junior this year though, meaning he has a much better chance of posting a higher passing efficiency than he did a season ago. Given that trend and the fact that he began to get real name recognition towards the end of last year, Price is not a bad choice as a dark horse Heisman candidate.