Going into the sixth week of the season, the San Diego Chargers are ranked towards the bottom of the league in run defense. 29th to be exact. A teams run defense always starts up front on the defensive line and works its way out.
The Chargers have preferred a 4-3 alignment recently, but when they have been in their base 3-4 alignment, one constant has been Sean Lissemore at the nose. Sean Lissemore is a tough player, who's effort is always there. The problem with Sean Lissemore is that he's not a nose tackle capable of taking on multiple blockers needed for the scheme to succeed.
Defensive Coordinator John Pagano prefers his nose tackles to attack gaps rather than take on multiple blockers, but Lissemore does neither at an acceptable level. He isn't quick enough to penetrate gaps, and he isn't big, or powerful enough to take on multiple blockers. Too often you will see Lissemore get blocked by a lone offensive lineman, which in turn frees up other linemen to reach linebackers on the second level. A linebacker should be able to shed blocks successfully, but he should not have to be depended on to do it every down.
A quarterback can succeed without a good offensive line in front of him. Philip Rivers is an example of this. He however can't be counted on to maintain a high level of play throughout an entire season with a sub-par line. It's just an unrealistic. Linebackers are the same way. They need to be allowed to roam and make plays.
The Chargers have a budding nose tackle on the team ready for this job in Ryan Carrethers. He is the ideal nose tackle, with a 6'1 333lb frame, great functional strength, and an improving technique.
Here you can see some examples of Carrethers taking on multiple blockers to free up linebackers.
And here is an example of the strength Carrethers plays with.
Now here is Sean Lissemore getting single blocked, freeing up the guard to get to the linebacker on the second level
Despite this, Lissemore still gets more than three times as many snaps as Carrethers. Lissemore to date has taken 37.4% of the total defensive snaps, compared to Carrethers' 10.4%. If the Chargers are to right the ship, Ryan Carrethers must be allowed to steer it.