Brown, a redshirt junior, will forgo his final year of eligibility and hire an agent.
A year ago, Brown said he would not leave Oklahoma until he received a first-round grade. In November, he acknowledged he was unsure about whether he would enter the draft.
"No, it's too early for me to say that," Brown told. "It's still a lot of football left, and I only focus on one week at a time. Obviously, I love it here, and there's a lot of things to look forward to in the future, but as far as the NFL, I don't know yet."
It's hard to find any real reason for Brown to stick around. CBS Sports ranks him as the best offensive tackle and fourth-rated player overall in the class. Given positional scarcity, it's possible he winds up becoming a top-five pick by draft night.
Listed at 6'8" and 360 pounds, Brown might wind up being a right tackle at the next level. Guys his size are typically mauling run-blockers rather than the nimble left tackles capable of fighting elite pass-rushers off the edge.
Brown is quicker than most guys his size, though, so whichever team drafts him will likely wind up giving him a chance to win a spot on the left side.