Is pressure hurting Matthew Stafford's downfield passing?

Matthew Stafford is averaging 6.46 air yards per attempt, on pace for the lowest such total of his career. Jake Roth/USA TODAY Sports

ALLEN PARK, Mich. -- Matthew Stafford has been playing hurt for three halves now -- first with a right arm injury and then bruised ribs.

The Detroit Lions quarterback has taken multiple hard hits over the first two weeks of the season, leading to him being at least in a lot of pain and quite sore.

One of the areas where Stafford’s injuries could hurt is throwing downfield. Lions coach Jim Caldwell wouldn’t say whether or not this is true, but he did say sometimes the pressure Stafford faces has kept him from reaching the deep progression in plays.

"Pretty much every route we have, not every route but the great majority of them, have a deep component, an intermediate component and a dump-off," Caldwell said. "What we try to do is work through the progression, and whatever they give us, we take."

Stafford didn’t go downfield often Sunday, averaging 6.00 air yards per attempt -- the 11th-worst air yards average of his career. However, this is not unexpected for him against Minnesota. Six of his 11 worst average air yards per attempt games have come against the Vikings, and this was better than three of his previous four games against Minnesota.

So far this season, Stafford is averaging 6.46 air yards per attempt -- down almost 1.4 yards per attempt from 2014 and is on pace for his lowest air yard average in his career. Of course, Stafford has actually thrown for more air yards per attempt when he has been pressured this season (8.12) than when he has not (6.06).

Again, tough to say whether or not his injuries, play calls or opposing defenses have limited him.

When Stafford hasn’t faced pressure, he has looked pretty good and made smart decisions a lot of the time. He also has looked a lot more comfortable during two-minute and hurry-up situations, where the Lions are primarily in shotgun with a single back, three receivers and tight end Eric Ebron.

In the 12 different personnel groupings with a singleback, three-wide set with one tight end, Stafford is 42 of 67 for 443 yards with four touchdowns, three interceptions, an 83.1 passer rating and 58.3 QBR.

The Lions have run 12 groupings with personnel other than the three wide receivers, one tight end and a running back and Stafford has completed 9 of 16 passes for 89 yards, no touchdowns, no interceptions, a 72.1 passer rating and a 40.0 QBR.

Stafford had a 67.1 QBR overall last week -- up from 34.3 against San Diego. His passer rating declined from 83.5 against the Chargers to 79.6 against Minnesota. His yards per attempt also decreased dramatically, from 8.20 against San Diego to 5.40 against the Vikings.

When Stafford was considered pressured against Minnesota on Sunday, he completed 2 of 7 passes for 31 yards -- including a touchdown pass. He had a passer rating of 85.1 and a QBR of 51.1 against pressure in Week 2. He was actually the No. 10 quarterback in the NFL last week under pressure according to QBR.

Stafford was pressured on 15.5 of dropbacks Sunday against Minnesota -- way down from the 32.3 percent pressure on dropbacks he saw against the Chargers. Of course, the sample size was much larger against the Vikings since he had 53 attempts Sunday compared to 30 in Week 1.

The blitz-per-dropback stayed fairly constant as the Vikings blitzed him 19 percent of the time, and San Diego blitzed 19.4 percent of the time.

When he wasn’t pressured, he completed 30 of 46 passes for 255 yards, a touchdown and an interception.

Stafford also got rid of the ball much faster, perhaps an explanation of his small air yards average. He averaging 2.39 seconds before a pass and 2.16 seconds inside the pocket. Those numbers are actually similar to his last game against the Vikings, where he got rid of the ball in 2.33 seconds and was in the pocket for 2.14 seconds in Week 15 last season.

Between San Diego and Minnesota, he has an 81.0 passer rating this season -- No. 25 in the league -- but his QBR of 54.2 is 19th, higher than Drew Brees, Peyton Manning, Andrew Luck, Joe Flacco and Eli Manning.

Advanced statistics in this post come from ESPN Stats & Information. Follow ESPN Stats & Information on Twitter @ESPNStatsInfo.