2-3-10: “A blindside block is a block against an opponent other than the runner, who does not see the blocker approaching.”
9-4-3-n: “No player or nonplayer shall … Execute a blindside block outside of the free-blocking zone with forceful contact unless initiated with open hands.”
This definition is broad and doesn’t only include the scenario you described, it covers any scenario/play where this type of block occurs.
Your questions:
1. It is a personal foul for an illegal blindside block, 15 yards.
2. Officials look for players “going against the grain / flow of traffic” as an indicator that a blindside block may be about to happen. If someone is running the opposite direction of everyone else, usually they are about to lay someone out. Yes, the rule requires forceful contact. We interpret that as a blow-up type of hit, usually with the shoulder, head, forearms, etc. If the player is hit hard enough to put him immediately to the ground, that’s usually an indicator of forcefulness. But depending on size of the players involved, it may not put the player on the ground. The direction of the blocker matters in the sense that the approach is outside the field of vision of the opponent.
3. To legally execute a blindside block, it either needs to be a.) in the free blocking zone (think tackle box in NCAA, but there is no “tackle box” in high school - free blocking zone is a close equivalent), or b.) executed with open hands and arms extended. If hands aren’t open or arms aren’t extended in front of the blocker, they’re at risk of a foul.
