CLEMSON — Clemson’s biggest weakness, its defensive backfield, was addressed in a big way on National Signing Day.

Clemson picked up five-star corner Mackensie Alexander today. He is the No. 4 overall player in the 2013 class, according to ESPN.

The other significant undecided player to chose Clemson on signing day was guard Tyrone Crowder, another top 150 ESPN player, who became Clemson’s 23rd and final signee around 4 p.m.

Alexander said he connected with Clemson coach Dabo Swinney.

“He’s a good guy. He’s a church guy like me,” Alexander said. “He made it from the bottom to the top, you know. The staff, Coach (Mike) Reed, I trust those guys.”

Clemson coach Dabo Swinney said Clemson hit on needs.

“This is an awesome day - this going to be another top-15 class, and these are guys who had a lot of options,” Swinney said.

“It’s a dynamic group, with a big emphasis on defense, and in particular defensive backs.”

Clemson also added three other defensive backs that were not previous commitments: four-star prospect Adrian Baker, a former Florida State commitment; and three-star prospects Korrin Wiggins, a former North Carolina recruit, and Ryan Carter, one of the top defensive backs in Georiga.

Those signing day additions eased the loss of missing on elite defensive ends Robert Nkemdiche, Carl Lawson and Elijah Daniel, and five-star defensive tackle Montravius Adams, who chose Auburn over Clemson this morning.

The Tigers also received letters of intent from RB Wayne Gallman, WR Kyrin Priester, RB Dorian O’Daniel, RB Tyshon Dye, ATH Jayron Kearse, DE Dane Rogers, Jr., DB Marcus Edmond, OL Maverick Morris, LB Ben Boulware and ATH D.J. Greenlee, DT Scott Pagano and DB Cordrea Tankersley as of 1 p.m.