Antonio Brown has an on-field weakness. Is it a blip, or is he declining?

Clark: Stacked Pats get even deeper with AB (1:14)

Ryan Clark states that Antonio Brown is going to have to learn how to be part of a squad and not a leader. (1:14)

Antonio Brown has a major weakness, and it has nothing to do with his helmet, feet or wallet.

Last season, before all the drama that led to Brown's release from the Oakland Raiders and near-immediate signing with the New England Patriots, he caught 100 passes for a sixth consecutive season with the Pittsburgh Steelers while putting up 1,297 yards and a league-high 15 touchdowns. On the surface, it looked like just another year as one of the game's top wideouts.

Digging deeper into the now-31-year-old's performance, however, reveals a worrying trend and a sign that he might be declining. The new Patriots wideout struggled against press coverage -- and the rest of the NFL caught on. It's a trend that would have been more problematic playing with Derek Carr in Oakland, California, than Tom Brady in Foxborough, Massachusetts, but one that could still slow Brown anyway. Let me explain.