There are four theories as to why the Vikings' passing game is stuck in the mud. In reality, they're probably all connected, but the trick is figuring out which is the most responsible for the problems.

1) The offensive line is bad at pass blocking and doesn't give Teddy Bridgewater enough time to make even simple progressions.

2) The Vikings' receivers aren't getting separation and aren't getting open, so even when Bridgewater has time he has nowhere to throw.

3) Bridgewater himself is being too tentative with the ball and seems to be no more than a game manager who can help you not lose a close game but can't help you win a tough one.

4) The offensive philosophy and plays designed by Norv Turner and co. aren't suited to the personnel and are easily counteracted by defenses.

The average fan would probably rank the problems like this: 1) Bridgewater/offensive line tie. 3) Norv Turner. 4) Receivers.

Football Outsiders, however, has a good film study on Bridgewater's most recent game against the Seahawks. In some ways, this is an unfair sample because it was easily the offense's worst game of the season (yes, even worse than the 49ers game). But in other ways, it's the perfect sample because the Seahawks are a good team — the kind the Vikings will have to defeat at some point to go from having a nice season to having a very good season.

So let's break down their breakdown and try to get to the root of this thing.

OFFENSIVE LINE

The takeaways from their film study are that the root of the problem is the Vikings' offensive line, which was already going to be bad before losing two starters to injury. There are numerous examples from the Seattle game in which the Seahawks got quick pressure using just four-man rushes, even against maximum protection. In many cases, it's not just one rusher getting pressure. It's a good illustration of how on many plays, especially in that game, Bridgewater just didn't have a chance.

RECEIVERS

There are also examples of plays in which receivers aren't able to get open. Some of this is because of the failures of the offensive line; if you can get pressure with four rushers, that leaves a lot of guys in coverage and a hard time for receivers to get open. If the Vikings are putting fewer eligible receivers into their routes because they need to block, and those blockers are still allowing pressure, the problem is magnified. FBO characterizes the Vikings receivers, as a whole, as "one of the least talented groups in the league, but it could be more productive in a better situation."

Interestingly, I talked to Vikings WR Charles Johnson in the locker room Tuesday and asked him specifically why Bridgewater hasn't been throwing to wide receivers as much recently (as I noted in a different post, 60 percent of his completions through seven games were to WRs, while only 36 percent have gone to WRs in his last five).

"I don't know those statistics, but I don't think any of the receivers care," Johnson said. "If we're not open deep, check it down as long as it's a positive play. We're just trying to win games. It doesn't matter how we do it."

Then I asked him if he thinks receivers are getting open. Keep in mind that Johnson's role in the offense has diminished as Stefon Diggs' role has evolved, to the point that Johnson was only on the field for a season-low seven snaps against Seattle.

"Personally for me, I always think I'm able to get open no matter what. You never know what the quarterback sees. We think we're open all the time, and we want the ball," Johnson said. "But there's a lot that goes into it. We just want to win games. Whether it's running the ball or catching the ball, we'll do both."

Is that just a receiver's mentality, or do you legitimately think you're open, I asked.

"I'm pretty much open all the time," Johnson said, though he also laughed because he knows the cliche is that every receiver thinks he's always open.

COACHING

Football Outsiders made an astute observation about the Vikings going away from having Bridgewater in the shotgun to jumpstart their running game earlier in the season. The switch didn't perfectly coincide with the increased throws to checkdown receivers, but the two figure to be related. It's a conundrum that I'm not sure the Vikings will fully solve this season, but it's a problem: Bridgewater is better playing out of the shotgun, when he has more time to hit receivers on intermediate crossing routes. Peterson is better in a traditional QB under center alignment, where he can get a full head of steam, read his blocks and exploit his jump-cut ability.

When the Vikings won five in a row with Peterson largely leading the way, the move looked smart. Against better teams, though, being one-dimensional hurts. When you struggle to run out of the shotgun and struggle to throw under center, defenses have a pretty good idea of what they want to do to stop you in both formations. FBO concludes that if the Vikings want to kickstart their offense, they need to put Bridgewater back in the shotgun and give Jerick McKinnon more snaps.

BRIDGEWATER

The film study absolved Bridgewater of a lot of the blame, which is interesting but not crazy. Any study of one game, with only a handful of plays highlighted, can reach pretty much any conclusion it wants. But FBO is a respected site that does a good job, so let's assume their conclusions are correct when they say this:

"There aren't many examples of Bridgewater holding the ball too long this season. There are examples of him holding the ball for a long time, but it's generally because there are no options open to him and he is trying to create plays either with his feet or as a passer. That's not to say Bridgewater has been flawless this season, but his issues largely remain confined to his ability to throw the ball deep down the field accurately."

In the final analysis, I'd say the offensive line is the root of most of the passing game's problems. If the line was better, receivers would have more time to get open, Bridgewater would have more time to make decisions even in traditional dropbacks, defenses would have to honor more possible outcomes and coaches would have more options.

The lesser problems are with Bridgewater: a tendency to hold the ball too long/play it too safe and an inability to hit on plays downfield when given the time and space; receivers: an underwhelming ability to get open, in spite of what Johnson says; coaches: a lack of creativity.

Given all that, though, the most interesting conundrum is whether the Vikings are willing to trade off production from Peterson for more from Bridgewater by putting him back in the shotgun more often. That would mask some of the line's problems, give Bridgewater and his receivers a little extra time and possibly open up the passing play book a little more — at the expense of Peterson's comfort level and production, or possibly at the expense of his playing time if McKinnon saw more snaps.

The results through eight games were in favor of Bridgewater under center. Per Pro Football Focus, the Vikings went 2-2 through their first four games while using shotgun snaps on 58 percent of plays; then ripped off wins in their next four games using the shotgun just 42 percent of the time.

But it could be said that against better teams lately — the Packers and Seahawks specifically — the conservative approach that tries to feed Peterson the ball from under center renders the offense pretty ineffective.

As such, if for no other reason than to try something new in a game in which points will be at a premium, I'd love to see the Vikings try more shotgun with Bridgewater against Arizona. They're not going to fix the offensive line on the fly. Their best hope is tinkering with the scheme to see if that can ignite their passing game. That it will come at the expense of one of the greatest running backs of all time is a gamble, but it's one worth taking.