How do you identify eligible/ineligible recievers?

[HLin NC]

What exactly is a covered up player?

Most commonly applied to the normally eligible TE where the SE or Flanker is on the line of scrimmage along side him

i.e. SE TGCGT TE FL


the flanker has "covered up" the TE in this formation, thus making him a lineman.
As long as he doesn't go downfield (expanded neutral zone) on a pass beyond the NZ or its a running play, he's legal. A power running team will line up like this all night with no problem.

To be legally downfield, the formation would need to be thus-

SE TGCGT TE
FL



now the TE is on the end of the line and eligible.

Covered up can also happen when a slot receiver lines up incorrectly on the LOS with the end.

SE FL TGCGT TE