A simple Google search for "Norv Turner Genius" will reveal all you need to know about an offensive coordinator with a long resume and reputation. For every positive story about Turner's pedigree, there's a negative article or comment in the other direction.

Turner this season has already been involved in those highs and lows — a nice week 1 plan and a 500-yard outburst against Atlanta, but four weeks in which the Vikings failed to top 300 yards or 10 points.

An offensive coordinator is a lot like a pitching coach in baseball — influential in dictating a lot of strategy and performance, but ultimately at the mercy of the athletes executing the plan.

Here, then, is an attempt to differentiate between the things that are relevant explanations for the Vikings' offensive woes and which are just excuses, as they relate to Turner.

*Adrian Peterson: Four of the five games the Vikings have played without Peterson have been dismal. We can argue about the wisdom of building an offense around a running back in 2014, but we cannot argue about the influence of Peterson's absence. Conclusion: 70 percent explanation, 30 percent excuse.

*Injuries: In addition to missing Peterson, the Vikings have also sustained key injuries at QB, tight end (Kyle Rudolph) and on the offensive line (Brandon Fusco). Rudolph figured to be a key member of the offense, while playing three starting QBs in the first six games is hardly ideal. That said, every team is going to deal with injuries during a season. Conclusion: 50 percent explanation, 50 percent excuse.

*Offensive line play: In two wins, the Vikings have given up 0 sacks. In four losses, Minnesota has allowed 22 sacks. There's no doubt poor offensive line play has influenced the offensive woes, and Fusco's injury has played a part in that. But if we're doling out percentages based on what Turner and other offensive coaches have control over and what is beyond their control, offensive line play would seem to be coachable. Conclusion: 50 percent explanation, 50 percent excuse.

*Play-calling: This would seem to be something Turner has 100 percent control over and therefore there is no excuse, but it's also influenced by how much confidence the offense has in the line play, the quarterbacks, the receivers and the running backs. You can only scheme so much. Conclusion: 30 percent explanation, 70 percent excuse.

Overall: Basically it's a split. There are circumstances that have led to the Vikings' offensive woes and hurt Turner in his ability to do his job … but they don't fully explain why the offense has been as bad as it has been.

We asked Turner on Thursday how often he has gone from being a "genius" to "not a genius" in a short amount of time.

"Anyone who has coached a limited time or a long time in this league knows this is a week-to-week league, and every week presents a whole new set of circumstances, a whole new challenge," Turner said.

As of now, there have been more down weeks than good weeks. If that continues, and the Vikings fail to adapt (and score), it will be more than fair to wonder if Turner should shoulder even more of the blame.