I'll make this amendment to the original post. When I talk about dumb players, I'm talking purely about an inability to play mentally disciplined football on a consistent basis.
Of course I don't believe Suh to be an unintelligent person. He's always come across as a thoughtful and independent thinker. But I would argue that he gets baited a lot on the football field. It's one thing to be a quick step, penetrator at DT, but sometimes Suh will be so quick to angle his rush, that he gets easily washed out the backside of the play. Another example is Landry. Landry has a gift for picking up YAC, but sometimes his penchant for backtracking to make an extra cut costs the offense valuable yards. Grant does the same thing.
We have some exceptional athletes on this team, and I believe a little more self-awareness and discipline can harness their talent.