The Jacksonville Jaguars had one of the worst offensive lines in the NFL for the 2012 NFL season, giving up 50 sacks on the season and ranking as one of the worst rushing teams in the NFL. It wasn't simply just because the players on the offensive line were bad however, it had a lot to do with injuries and inconsistency.
For the 2013 season, with health on their side, the Jaguars offensive line as a whole could be drastically improved from the last two seasons.
Left tackle Eugene Monroe has been on a steady upswing with his ability and is one of the top left tackles in the NFL. At the left guard position, Will Rackley struggled as a rookie making the big leap from Lehigh to the NFL and needed to get stronger, but after missing last season with an injury he's finally healthy and has two full offseasons in a weight training program. Center Brad Meester is back for at least one more year, and while his skills are eroding, he's still a serviceable player on the interior. Uche Nwaneri played on one leg most of the 2012 season, but prior to that has always been a reliable blocker.
Then you insert what should be a massive upgrade to the right tackle position in first-round pick Luke Joeckel, and the Jaguars could have one of the best offensive lines they've had in four or five seasons.
This isn't to say it's instantly going to upgrade the offense, but if the unit can stay healthy heading into the season, it could be the most improved unit as a whole on the Jaguars in 2013.