Should the San Diego Chargers look for another nose tackle?

Nov 17, 2013; Miami Gardens, FL, USA; San Diego Chargers defensive end Sean Lissemore (98) sacks Miami Dolphins quarterback Ryan Tannehill (17) during the second half at Sun Life Stadium. The Dolphins won the game 20-16. Mandatory Credit: Joe Camporeale-USA TODAY Sports
The San Diego Chargers struggled in the middle of the defense last season using Cam Thomas to lock down the nose tackle position. He was eventually pushed out of the starting lineup by Sean Lissemore. Now, Lissemore has been given the starting job this year without much competition from anyone else on the roster.
The team did draft Ryan Carrethers to rotate on the defensive front, but will he be enough? The team also has Kwame Geathers to push for playing time as well, but both players still seem to be a season away form making an impact.
There isn’t much depth at the position behind Lissemore. Carrethers was taken in the 5th round this season and has to develop. Geathers got some playing time last season, but has he done enough to move to the next level this year?
The coaching staff likely has been evaluating the talent at the position during these OTAs and they have to be thinking about bringing in a possible veteran onto the roster. There are a couple of guys that are available that could fit in nicely on the roster: