Antonio Brown signed a four-year, $68 million extension with the Steelers on Monday, making him the NFL’s highest-paid receiver.

But Brown says he’s not done working.

Shortly after the deal was made official, Brown tweeted a photo of a negative pre-draft scouting report from the 2010 draft. The report pegged Brown as a late-round, marginal draft pick as a prospect from Central Michigan.

The scouting report read:

“Brown’s strength and instinct deficiencies will make it difficult to separate at the next level. Character concerns could limit his appeal and knock him off the draft boards.

NFL projection: Late draftable pick.

Brown was selected by the…