For Sapp I think work ethic equals the love for the game and wanting to give your all because you want to be the best. Not the smartest move to be 420ing it up, but the concerns of taking plays off, lots of plays off because you have the meh about football is what is troubling him. He is no choir boy but might have a point, but as others seem to agree the players and coaches on this team will kick that right out of the field!
The only reason not to, would be to hold out for trade offers or keep options open. So, if the team won't go on record saying he's their pick, how could Clowney shut down his self-marketing?
I think a more apt question is: Did he injure himself? Think about it. What if something's nagging him which would negatively impact future workout performance, thereby negatively affecting his draft stock.... yet, admitting the injury as the reason he can't work out, would also negatively impact his draft status? Answer: Back all physical activity down, play poker cards close to chest and keep a stone face.
Not saying this is what has happened, but it's a viable spin on the story. It's also possible the dude is overworked and stressed out after months of training and interviews. Working out while exhausted can often lead to injury.
Sapp is a complete moron...with that said, Clowney is lazy and wont be much better then average