The NFL just finished Week 6, and the Bears are… fine. They're 4-2 in a good division with the two losses going against the sort of teams they have to beat if they're going to turn "fine" into something better than last year's fine 10-6 team that missed the playoffs. In other words, a pretty typical Bears season.

Lost in the ambivalence has been an encouraging fact: this is Jay Cutler's best season as an NFL quarterback:

It's far too early still to cast a verdict on whether this 2013 version of Cutler is the best yet. The jury still needs 11 more weeks of evidence for deliberations. But statistically, significant signs have surfaced. Through six games, Cutler has a passer rating of 95.2, better than his single-season best of 88.5 posted as a rookie in Denver in 2006.

But Cutler only played five games in 2006, and passer rating is kind of a limited measurement. By most metrics—not fancy ones, just ones you'd expect to represent a quarterback—2006 wasn't Cutler's best year. He had a 59.1 completion percentage, the lowest of his Denver years; he got sacked a lot (13 sacks in five games, two more than in all of 2008); had the highest interception percentage of his Denver tenure, the lowest net yards per attempt, and so on. He was a rookie.

The Bears acquired Cutler after the 2008 season, a better candidate for his best season, and his only Pro Bowl season. His top-line stats were good: 4,526 yards (third behind Drew Brees and Kurt Warner) with 25 touchdown passes (seventh in the NFL), 10th in yards per attempt. The 18 picks were a bit rough, but it was heretofore his best season by ESPN's quarterback rating, Football Outsiders' advanced metrics (good for sixth-best among quarterbacks), and Advanced NFL Stats' system.

And he was sacked 11 times the whole season, for a sack percentage (PA/sacks) of 1.8 percent. To put that in perspective, the only quarterback with a better sack percentage during a single season in Cutler's career has been Peyton Manning in 2009—at that point, arguably the best season of Manning's career.

We know what happened after that. Cutler was paired with converted kick returners for his best recievers for the first three years of his Bears career. After being sacked 38 times over his only two full seasons as a Bronco, he was sacked 35 in his first year as a Bear, 52 in his second—he was sacked on ten percent of his pass attempts—23 in 10 games in his fourth, and 38 in his fifth year.

Chicago had some fun with this while I was away, pulling together a gallery of Cutler's sad sack face. To put his difficult 2010 in perspective, a 10 percent sack rate is Tim Tebow/JaMarcus Russell/J.T. O'Sullivan territory.

As a result, Bears Jay Cutler completes 60.3 percent of his passes (down from 62.5 as a Bronco); averages 5.53 net yards per pass attempt (down from 6.40); throws picks 3.5 percent of the time (up from 3.0); and has a passer rating of 83.4 (down from 87.1).

But this year Bears Jay Cutler is getting the protection he had in Denver: his four percent sack rate is identical to that of his three years as a Bronco, and it puts him just behind Peyton Manning and Matthew Stafford, and tied with Philip Rivers and Matt Ryan in 2013. And everything has flowed from there. Here's a comparison of Cutler's 2008 and 2013 seasons:

  2005 2013
Completion percentage 62.3 65.9
Interception percentage 2.9 2.8
Adjusted yards per pass attempt
(Advanced NFL Stats)
5.8 5.7
Adjusted net yards per pass attempt
(Pro Football Reference)
6.61 6.79
QBR 72.3 73.5
TD/INT vs TD/INT pace 25/18 32/16

This year is really Cutler's first that he's been a full-fledged offense to work with. J'Marcus Webb is on the Vikings' bench; Kellen Davis is on the Seahawks' bench; the Devin Hester experiment is over; Alshon Jeffery has given Cutler a bigger second option than Earl Bennett. The Bears might still be middling this year, but they've finally got the quarterback they wanted.