It’s been a difficult season for the LSU defense and DC Bo Pelini has pinpointed a clear reason why.

The first-year LSU defensive coordinator believes the woes can be attributed to the kind of players he inherited. Previous LSU defensive coordinator Dave Aranda built his unit with players designed for his 3-4 scheme.

Pelini now has LSU operating out of the 4-3.

“It’s a big difference,” Pelini said to the LSU Radio Network via The Advertiser. “We have guys that were recruited to play in a 3-4. It’s not exactly the type of personnel you would recruit to play in a 4-3. It’s really foreign to those guys as far as the understanding of linebackers playing off the football. Then your down guys are playing different techniques and gaps, and it takes some time. And it takes some time for us as coaches to learn what your guys can do and what they can’t do.”

However, LSU coach Ed Orgeron doesn’t agree with Pelini’s assessment for a specific reason.

“I don’t think that has a lot to do with it,” Orgeron said during Wednesday’s SEC coaches teleconference, via the The Advertiser. “Because of the fact that most of our mistakes were on explosive passes in the coverage. Now, whether you’re playing a 3-4 or a 4-3, the same coverages can still be run out of both fronts.”

LSU has allowed at least 40 points 3 times this season and is allowing 302.9 passing yards per game. The Tigers are giving up 140 rushing yards per game as well. LSU made strides last week in a loss to Texas A&M, though. The Aggies finished with a season-low 267 yards.

Things won’t get any easier for the LSU defense this week. LSU (3-4) will be making up its postponed game vs. visiting No. 1 Alabama (8-0) and Heisman Trophy candidate Mac Jones.  Kickoff is set for 8 p.m. EST and will be televised on CBS.