COLUMBIA — After a junior season that saw him emerge as a dominant force on defense and a bit of a lightning rod off it, Missouri defensive tackle Sheldon Richardson officially declared for the 2013 NFL Draft on Friday.

“This has been my dream ever since I was a little kid,” Richardson said in a statement. “It’s still not easy leaving Mizzou like this, but I know I’m ready. I really appreciate all of the support I got here at Mizzou, and I know that they will help me and my family with this next step. I’ll always be a Tiger.”

Richardson, a 6-foot-4, 295-pound native of St. Louis, had a breakout year for the Tigers, racking up 75 tackles, 10½ tackles for loss and four sacks. He had the second-most tackles for MU this season, something rarely done by an interior lineman, and had the most tackles among all players at his position in the Southeastern Conference.

“I’ve always said that when guys have opportunities like these, if they’re ready to go, then they should go,” said MU coach Gary Pinkel, who predicted earlier this week Richardson would enter the draft. “I have no doubt that Sheldon is ready to play in the NFL, and while we’d love to have him for another year, the important thing is that this is the right decision. It will be fun watching him play on Sundays.”

Richardson emerged as a full-time starter this year after arriving at Missouri from junior college before last season. He started two games as a sophomore, finishing the season with 37 tackles and eight tackles for loss despite nagging injuries. He healed over the offseason and lost roughly 20 pounds.

This set the stage for a dynamite junior season that saw his stock rise significantly — he is currently listed as No. 21 player on ESPN draft analyst Mel Kiper Jr.’s big board, and could be the sixth player to be taken in the first round during Gary Pinkel’s 12-year tenure at Missouri.

There were also some rough spots. The first was before the SEC opener against Georgia, when Richardson declared that the Bulldogs played “old-man football” and said nobody in the SEC could touch the Tigers if they executed properly. Richardson wasn’t allowed to speak to reporters for a month after those comments.

Richardson also made waves after MU’s disappointing 19-15 loss to Vanderbilt on Oct. 6, when he could be heard yelling at his teammates in the locker room during Pinkel’s postgame news conference.

“I was frustrated,” Richardson said at the time. “Just emotions coming out … we put a lot into this, man … put in hours of gameplanning, hours of practice in. We put a lot into this season, and we want more than what we’re getting out of it.”

Richardson played well a few weeks later at Florida — a 14-7 road loss in which he had a blocked field goal and made several big plays — but again raised eyebrows when he was suspended against Syracuse on Nov. 17 for a violation of team rules.

Missouri lost that game 31-27, a devastating home defeat in which the Tigers gave up 508 total yards. Richardson returned for the season finale at Texas A&M and finished with five tackles in the 59-29 loss.