The last two weeks have been much different for the LSU defense than the first two weeks were.

The Tigers were dominant in victories the first two weeks. They shut out BYU, held it to minus-5 yards rushing, 102 yards passing and 97 total yards. A week later against Chattanooga, the Tigers allowed 10 points, 68 rushing yards, 174 passing yards and 242 total yards.

Then came the SEC opener at Mississippi State and everything was much worse for LSU, which allowed 285 rushing yards, 180 passing yards and 465 total yards in a 37-7 loss.

Last week against Syracuse, the defense looked much better in the first half, allowing just three points, but in the end the Tigers had allowed 308 of 384 total yards through the air in a challenging 35-26 victory.

Now comes a final non-conference game against Troy on Saturday night in Tiger Stadium before 25th-ranked LSU returns to SEC play Oct. 7 at Florida.

LSU is ranked 23rd in the nation in total defense (297 yards per game).

The loss at Mississippi State came as the Tigers stepped up in class, but the performance against Syracuse suggested that there was more to the inconsistency than just the quality of competition.

LSU is lacking depth on the defensive line, which was exacerbated by injuries to end Rashard Lawrence and tackle Ed Alexander as well as the ejection of reserve Neil Farrell Jr. for targeting, a punishment that carried over for the first half against Syracuse.

Lawrence returned against the Orange and contributed five tackles, two for loss, one of which was a sack. His presence also allowed Greg Gilmore to return to his natural nose tackle position.

The reinforcements on the line contributed to Syracuse’s inability to run with any consistency, but the Orange kept hanging around a game that LSU seemed poised to break open after taking 11- and 18-point leads.

“We need to rotate better, and obviously we’re very thin,” Orgeron said of the line. “(Lawrence) does give us a big boost when he plays. We’re very thin, but we have to learn how to rotate our guys earlier in the first and second quarter so they’re not worn out in the third and the fourth. I think you’ll see an improvement in that this week.”

But Lawrence aggravated his ankle injury against Syracuse. He’ll likely sit out the week and LSU hopes he’ll be ready for Florida.

Linebacker Devin White has been one of the most consistent defenders and he had 13 tackles against the Orange.

The secondary has suffered injuries at safety; Ed Paris had season-ending knee surgery and John Battle was hurt against Syracuse. He had 11 tackles and forced a fumble before leaving the game for good in the third quarter. Orgeron said he hopes Battle can play this week.

Cornerback Andraez “Greedy” Williams has made the most big plays on defense, grabbing his third interception of the season on the first play from scrimmage against Syracuse. That set up a touchdown on the next play.

Credit: Derick E. Hingle-USA TODAY Sports

There were question marks about this defense entering the season because of inexperience. The Tigers lost their top five tacklers from last season and linebacker Arden Key, the leading tackler from last season and the school record-holder for single-season sacks, missed the first two games as he worked his way back from off-season shoulder surgery.

LSU's Arden Key had 12 sacks last season, second in the SEC.

Key has played in the last two games as he tries to regain his conditioning and game form. He has just five tackles, including half a sack, through two games but figures to get better as the season wears on, which should be a boost for the defense.

Orgeron said Monday that Key is “rusty, very rusty.”

The concerns about the defense might be less significant if the troubles of the past two weeks were the same, which would lead to a narrow focus for corrections. But the shortcomings manifested themselves in very different ways in each game.

Against Syracuse, the Tigers did much better up front but the Orange’s deception and fast pace led to three second-half touchdowns.

“We didn’t contain the quarterback well enough,” Orgeron said. “We lost contain many times. The quarterback went on edge and made some plays. The reversals got outside of us. We want to get lined up for pace tempo. Lot of times we weren’t lined up properly in our gaps.

“The thing that limited us a little bit was the speed in which they were running the plays. A lot of things we do are predicated on the strength of where the field is at, where the boundary is at. The strength of the formation, away from the strength of the formation. There is a lot of communication that has to go on there, and they didn’t give us enough time to get that done.”

Orgeron was bothered by the defense’s inability to get off the field more consistently after Syracuse converted 8-for-19 third downs and 2-for-3 fourth downs.

After the dominance of the first two weeks, LSU’s young defense has started going through growing pains.