Tackle-eligible play

In football, the tackle-eligible play is a forward-pass play in which coaches will attempt to create mismatches against a defense by inserting an offensive tackle (who is not normally allowed more than five yards down field on a forward-pass play), into an offensive formation as an eligible receiver, usually as a tight end or as a fullback. This is done by changing the formation of the offensive line, via positioning two linemen (including the "catching tackle") on one side of the center and three linemen on the other.

Under almost all versions of gridiron football, offensive linemen cannot receive or touch forward passes, nor can they advance downfield in passing situations. To identify which receivers are eligible and which are not, football rules stipulate that ineligible receivers must wear a number between 50 and 79. However, in some leagues, normally ineligible receivers may align as eligible receiver provided they inform the referee of such a change. Typically, a player must leave the field for a single play before returning to their original position.

The official NFL rules stipulate that an offensive player wearing uniform number 50-79 or 90-99 may not line up as an eligible receiver, with a violation being penalized as an illegal substitution. However, the rules provide an exception where such a player may become eligible if he declares his intent to the referee prior to the play. The referee then announces that the ineligible number "x" is reporting as an eligible receiver. This announcement is made using the referee's microphone so that spectators and the opposing team can hear. The eligibility is in effect for only one play; the report to the referee must be repeated before every play in which the offense plans to make the player eligible. Similarly, a player whose number is typically "eligible" must report himself ineligible to the referee, otherwise his team would be penalized for illegal formation. An example is when New England Patriots running back Shane Vereen did this in the 2014–15 NFL playoffs versus the Baltimore Ravens.

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