He's making up for lost time.
LSU's senior guard was named player of the year on The Associated Press All-SEC team announced Monday after leading the Tigers to the regular-season championship and a spot in the NCAA tournament.
LSU also claimed the coach of the year award, which went to Trent Johnson for turning around a program that slumped the last two years under John Brady.
Mississippi freshman Terrico White was named newcomer of the year.
Thornton was a top prospect coming out of Tara High School in Baton Rouge, La., but his career took a two-year detour because of academic problems. After a stint Kilgore College in Texas, he finally signed with his hometown team.
His first season at LSU was a personal success; Thornton was the SEC's second-leading scorer at 19.6 points a game. But the Tigers struggled as a team, which led to Brady being fired midway through the conference schedule _ less than two years after reaching the Final Four.
Johnson was lured away from Stanford after the season and immediately set about to change the mind-set at LSU. He knew he had plenty of talented players, but demanded everyone _ Thornton included _ devote more time to the less-glorious aspects of the game.
His star heeded the message.
"Marcus has meant everything to our team," Johnson said Monday. "He's a young man who two months ago made the comment that he wanted to be playing meaningful games in February and March. He knew to do that, he had to do things other than scoring."
Not that Thornton has abandoned the offensive end. He's actually stepped up his average to 20.7 points a game, again ranking second in the SEC.
Surrounded by a veteran team that includes fellow seniors Garrett Temple and Chris Johnson, along with junior Tasmin Mitchell, Thornton led the Tigers to a 26-7 record, the SEC championship at 13-3, and a spot in the NCAA's South Regional
"This season as a whole has been a blessed season," Thornton said. "Who would have thought we'd be headed to the NCAA tournament this year. After the termination of coach Brady, coach Johnson came in with a philosophy and we got right to it from day one. His resume speaks for itself. He came in, did what he had to do, and we're headed to the tournament. This will be my first time going."
Johnson, who came to LSU after successful stints at Nevada and Stanford, said he's not surprised by the turnaround from last season's 13-18 mark.
"Obviously, there's some talent here," the coach said. "A lot of guys were injured in John's last year. If they had not had those injuries, he would probably still be here. For us, the key was whether they were committed to defending and rebounding and taking care of the ball. When things got tough, would they stay the course and not revert back to old habits?"
The Tigers stayed the course, clinching the championship with a week to spare _ at Kentucky's hallowed Rupp Arena, no less. Thornton scored 23 points in the 73-70 victory and celebrated in style, throwing the ball into the rafters after the horn sounded.
"We tried to mesh together really well early in the season, and it has paid off for us," Temple said after that game. "We have bought into coach's system and know that he knows how to win."
The Tigers did slump a bit after wrapping up their title, losing their final two regular-season games. They also came up short in the SEC tournament, falling to eventual champion Mississippi State in the semifinals. LSU was only given a No. 8 seed in the NCAA tournament and will face dangerous Butler in the opening round Thursday at Greensboro, N.C.
Thornton was a unanimous selection to the AP's first team. He was joined by the SEC's top scorer, Jodie Meeks of Kentucky (24.2), along with South Carolina's Devan Downey, Tennessee's Tyler Smith, Mississippi State's Jarvis Varnado, Florida's Nick Calathes and LSU's Tasmin Mitchell.
Varnado, Calathes and Mitchell tied for the final first-team spot.
Meeks stood out during Kentucky's disappointing season, breaking the school scoring record with a 54-point performance against Tennessee in mid-January. Downey was the league's third-leading scorer at 19.9 a game, also placed third in assists (4.5) and led in steals (3.0). Each was named to the first team on all but one ballot.
Smith led Tennessee at 17.2 points a game. Varnado is the nation's top shot blocker (4.7) and broke the SEC's season record with 165, eclipsing the mark of 157 he had shared with Shaquille O'Neal. Calathes led the conference in assists (6.4) and ranked second in steals (2.0). Mitchell shared the scoring load with Thornton at 16.3 points a game.
White, who averaged 13.7 points a game in his first season at Ole Miss, was among those named to the second team, along with Kentucky's Patrick Patterson, Auburn's Korvotney Barber, Alabama's Alonzo Gee, Ole Miss' David Huertas and Arkansas' Michael Washington.
Smith and Downey made the first team for the second year in a row, while Thornton and Calathes moved up from the 2008 second team. Patterson was a second-teamer for the second straight season.
The 61st annual AP All-SEC was selected by a 12-member media panel representing each of the conference's nine states.
The 2009 Associated Press All-Southeastern Conference men's basketball team released Monday, with name, school, position, height and class (u-unanimous choice to first team; t-tied for final spot on first team):
HONORABLE MENTION: Dominique Archie, South Carolina, F, 6-7, Jr.; Wayne Chism, Tennessee, F, 6-9, Jr.; Chris Johnson, LSU, 6-11, Sr.; A.J. Ogilvy, Vanderbilt, C, 6-11, So.
PLAYER OF THE YEAR: Marcus Thornton, LSU
COACH OF THE YEAR: Trent Johnson, LSU
NEWCOMER OF THE YEAR: Terrico White, Mississippi