The rising Minnesota Vikings have had a stellar offseason highlighted by an electric draft class. But concerns at positions of need continue to dog the young team, showcased by the concern the Vikings have at nose tackle.
The nose tackle may be the most important position in the Vikings' 4-3 Tampa 2 defense, and the reason is simple: blocking math.
On a typical running play, an offensive team has nine blockers to 11 defenders, given that the quarterback is rarely going to help block (unless he is Russell Wilson). This usually means that the safeties are left unblocked and the running back is on his own when he hits the second level. When this happens, the running back is likely to get four yards, which would be considered a "win" for the offense.
There are a lot of ways the offense will cheat this math by leaving defenders away from the play alone and putting more bodies at the point of attack. Sometimes, that means having a wide receiver cut-block a linebacker and leave the cornerback away from the play alone. Other times, it means pulling a guard or even a tackle.
But if the defense has a way of changing that math so that one linebacker goes unblocked, it's disastrous for the offense. A good nose tackle will stay in place and demand a double-team, lest he break free and make a play in the backfield.
If any defensive player can command two blockers instead of one, it frees up a linebacker (usually the weak-side linebacker) to make a play, which would be a "loss" for the offense.
The nose tackle's job is to be the player that messes up the blocking math for the offense and for that, he has to be stout against the run, difficult to move and a threat to make plays in the backfield.
This is especially true in an NFL featuring more read-option offenses, where the quarterback has the ability to "block" a defensive player by reading him and either freezing the player or forcing him to make the wrong decision. In that situation, the offense has gained a blocking advantage and can put blockers on a play-side safety if need be.
The nose tackle is also critical in passing situations.
Obviously, clogging up two pass-blockers makes it easier for the other pass-rushers to get to the quarterback. But it affects how the offense will call protection.
The nose tackle often gets enough attention that in an "over"-shifted scheme (like the one the Vikings run), the nose tackle will be aligned on the weak side of the formation, away from the tight end.
Because opponents will not want to leave an edge-rusher alone (especially if it is Jared Allen), they will likely call man protection to the tight end's side and slide protection on the nose tackle's side. Because the nose tackle will be the only player in his area, he will demand the weak-side guard and center's attention.
If he's not a threat to collapse the pocket, the center or the guard will handle the nose tackle by himself, and they will move back to either double-team the best pass-rusher or pick up blitzers.
More importantly, it won't make stunts or twists particularly effective. Without demanding to be blocked by two players, the nose tackle can't be used as a decoy when linemen twist around to confuse blocking assignments.
In slide protection, the center or guard will be free to pick up whichever pass-rusher enters his area (like Everson Griffen or Jared Allen). Then, the defense will have committed the sacrifice of a delayed pass rush and open running lanes for nothing.
Unfortunately, Letroy Guion doesn't seem fit for the role.
After being graded by Pro Football Focus as the single worst defensive tackle of 2012 (subscription required), the Vikings are correctly looking for a way to either improve his play or find a better player.
During several sessions of the CBA-designated Organized Team Activities (OTAs), Guion's backup Fred Evans has taken starting snaps. That hasn't always been the case, however, and Guion has started in a number of sessions as well.
Head coach Leslie Frazier told 1500 ESPN that the position coaches want to give Fred Evans a shot to start and have given him a significant opportunity to do so in several OTAs.
Of the two, Fred Evans has been the more athletic and explosive player, but he's been inconsistent with his play in the last seven years. While Evans sees more time in the backfield because of his greater penetration, he also gets moved around more and can be found on an island instead of a double-team.
As Evans is entering his eighth season, it might be a little too much to think that Minnesota has solved its nose tackle problem by moving him in as a starter. Still, Evans outperformed Guion in his backup time, something Pro Football Focus took note of in their new "NFL Daily" feature.
The performance difference wasn't very close, although that speaks much more to Guion's poor play than anything else.
The Vikings should be careful to automatically install an overperforming backup over a starter. Guion outperformed one-year free agent Remi Ayodele and actually looked much like a reasonable nose tackle in the 2011, despite playing more as a pass-rusher in previous years.
The transformation of Guion from a pass-rushing tackle to a run-plugging tackle looked to have worked out. But his 2012 was a demonstration that it may not have been the brightest idea to ignore one of the most important positions in the Tampa 2 defense.
Guion was originally a "3-technique" pass-rushing tackle designated to get to the quarterback and line up between the guard and tackle, not a "1-technique" defensive tackle lined up between the center and guard. A stark difference, Guion's conversion was a little surprising, given that he showed up to the combine undersized.
In fact, Ourlads scouting service pegged him as the kind of player a team wouldn't want to plug the run:
Good effort in pursuit. Takes good angles. Can slip a block. Doesn't stay blocked. Struggles to stack the run between the tackles. Lacks functional strength. Tendency to play high. Frame to get bigger. Makes his plays from tackle to tackle. Lacks the ability to control opponent with effective hand use. Opens up body and is vulnerable to blocks.
Fred Evans seems better built for the position. But like many of the Vikings' players one the defensive line, he is a little bit smaller. But he came out of Texas State better suited for the nose tackle position. He has explosiveness and an ability to rush upfield, but he also has the type of strength and agility needed to take on double-teams.
An arrest in Miami saw him packing his bags and heading to Minnesota. Stamina concerns initially trailed him, but his inconsistent play seems to be the biggest reason he hasn't seen starting snaps.
He did, however, put together a fantastic 2012 campaign and could be poised for a late-blooming breakout season.
While it's unlikely that an eighth-year vet will suddenly turn into a game-changer, his limited time (367 snaps) in 2012 speaks to improvement in his play, consistency and stamina that might mean he's a better fit at nose tackle.
His age (he's 29 years old, due to turn 30 during the season) is a good reason he won't be a long-term answer at nose tackle, but he might improve the Vikings at a position they sorely need to upgrade if they want to continue their appearances in the playoffs.
The Vikings will either need to sign a free agent after the 2013 season, trade for a nose tackle, draft one in the 2014 draft or hope that undrafted free agent Anthony McCloud has the tools they need to succeed.