also: unbalanced line · tackle over · tackle-over
Putting more linemen on one side of the center than the other. Legal, rare, and disruptive, because a defense's alignment rules are written assuming five linemen in the usual places.
2 meanings, all below. Jump to the one you heard.
The offensive line aligns with more players on one side of the center than the other, most commonly by moving a tackle to the other side of the formation, which is where "tackle over" comes from.
The reason it works is that it moves the edge. Defensive alignment rules are written in terms of the offensive line, so a defense that aligns by rule will align to a line that is not where it thinks it is, and a defender who believes he is the end man is suddenly inside somebody. Against a defense that does not check it, the offense gains a blocker at the point of attack without adding a player.
unbalanced line, tackle overtrips, split end, flanker and slotThe sense that actually costs teams points. Rearranging the line changes which players are on the line of scrimmage, and therefore which are eligible receivers, and an unbalanced formation that leaves a receiver covered up makes him ineligible whether or not anybody intended it.
This is also why officials at high school and youth level often want to be told about an unbalanced formation before it is used. **The specific rules are not stated here because they have not been checked against a current rulebook**, and a wrong eligibility claim is among the most damaging errors this glossary could publish.
Disproportionately effective at youth and lower high school levels, because defenses there align by rote and are unlikely to have practised a check. That is also the reason it is worth mentioning to the officiating crew pre-game rather than springing it.