LSU has three cornerbacks, three linebackers and two defensive linemen headed its way as part of the 2019 recruiting class. Five are rated 4- or 5-stars.

Too bad none of them will be eligible for the Fiesta Bowl. The Tigers could use them.

LSU learned this week that defensive tackle Ed Alexander is skipping the Jan. 1 game against undefeated and No. 8 UCF to prepare for the NFL Draft. End/tackle Breiden Fehoko already was declared out of the game because of injury.

Cornerback Greedy Williams paved the way for Alexander when he declared earlier this month that he was turning pro early and skipping the bowl game. The other starting cornerback, Kristian Fulton, also will miss the game after undergoing surgery for an ankle injury suffered against Arkansas last month.

Throw in the absence of linebacker K’Lavon Chaisson, who suffered a season-ending injury in the opener on Labor Day weekend, and No. 11 LSU has some serious holes on the defense.

At this point, Chaisson’s absence is the least significant because the Tigers finished the victory against Miami and won 8 of their last 11 games without him. Andre Anthony moved into his starting position and the adjustment period ended a long time ago.

But the other absences hurt the most. Especially the most recent ones from Williams and Alexander, which are the result of player choices and not injury.

Alexander and Fehoko had both dealt with injuries during the season and down the stretch Alexander emerged as a starter and a key player while Fehoko battled a biceps injury that ultimately required surgery.

With Alexander and Fehoko out, the depth on the defensive line will be severely tested by the Knights. The Tigers still have talent on the line with Rashard Lawrence, Glen Logan, Tyler Shelvin and Neil Farrell, but the rotation will now have to include less experienced players than it did for most of the regular season.

As for the absence of Williams and Fulton, Terrence Alexander and Kary Vincent Jr. are the most likely fill-ins, but others, including Kelvin Joseph, could also get added snaps as a trickle-down effect.

Williams, remember, had 6 interceptions as a redshirt freshman last year. His impact wasn’t as dramatic this season, party due to quarterbacks avoiding him, but he still helped neutralize a good chunk of the field.

LSU defensive coordinator Dave Aranda is paid handsomely to figure things out. And at least Alexander and especially Williams gave him some time to prepare for their absence. And he still has linebacker Devin White, chosen by his teammates as the Tigers MVP this season, safety Grant Delpit and other key starters.

But the Tigers are getting ready to play a really good offense, albeit without quarterback McKenzie Milton, who suffered a severe knee injury against South Florida on Nov. 23.

Redshirt freshman Darriel Mack Jr. replaced Milton and played extremely well in the AAC Championship Game. UCF twice trailed Memphis by 17 points and was down by 10 in the third quarter before Mack led a scoring blitz down the stretch.

He completed 19-of-27 for 348 yards and 2 touchdowns and ran 18 times for 59 yards and 4 touchdowns as the Knights prevailed 56-41.

Mack is 6-3, 230 pounds. A dual-threat QB from Norfolk, Va., he had offers from in-state Power 5 programs Virginia and Virginia Tech, not to mention nearby West Virginia, Maryland and UNC. He chose UCF.

Now he’s leading the Knights against LSU. Call it a battle of the backups.

LSU’s defense is a lot different than the Memphis defense, but the LSU defense that will take the field to start 2019 will be a lot different than the one that started the 2018 season.