Six NFL quarterbacks in need of improved accuracy

Both Derek Carr and Andrew Luck need to see an uptick in accuracy this season. AP Photo, Icon Sportswire

Last week, we looked at the 10 most accurate passers from the 2015 NFL season using a metric (C%+) that adjusts for where the ball is thrown. Most of the usual suspects made the list, but what about the quarterbacks at the bottom?

The bottom three were bad enough that none of these players figure to be a factor in 2016. Nick Foles (minus-6.6 percent) was released and went to Kansas City. Johnny Manziel (minus-4.9 percent) is currently not in the league. Ryan Mallett (minus-4.9 percent) is a backup in Baltimore.

Peyton Manning (minus-1.1 percent), who also ranked among the worst, showed it was time to retire after the first below-average season of his career.

But that still leaves six quarterbacks in the bottom 10 who figure to be a factor this year. The following is a look at those six quarterbacks, ranked by ascending C%+ from the 2015 regular season.

First, here is a refresher on how C%+ is calculated. The core idea is passing plus-minus, which estimates how many passes a quarterback completed compared to what an average quarterback would have completed, given the location of those passes. It does not consider passes listed as "thrown away," "tipped at line" or "quarterback hit in motion." Player performance is compared to a historical baseline of how often a pass is completed based on the pass distance, the yards needed for a first down, and whether it is on the left, middle or right side of the field.

Because we care only about whether or not the pass was completed with this stat, dropped passes can be accounted for favorably for the quarterback. Once we have the drop-adjusted plus-minus total, it can be divided by the number of passes to get an adjusted rate we denote as C%+.

A quarterback's C%+ is how many percentage points better or worse than average he was at completing passes.

1. Colin Kaepernick, San Francisco 49ers

C%+: minus-4.4 percent

Kaepernick started off his career in 2012 with a great C%+ (7.3 percent) in a vertical offense, but he has declined every year since. Always more of a "thrower" than a precision passer, last season was especially bad as Kaepernick struggled to locate receivers, let alone deliver accurate passes. The most troubling fact was that his average pass distance dropped to 7.7 yards beyond the line of scrimmage after being in the 9.5-9.8 range in the previous three seasons. So even though his passes were shorter, he was worse at completing them. Now you can start to see why he may be benched (again) for Blaine Gabbert in San Francisco.