The forward progress clock rules, explained also by Football Outsiders:
http://www.footballoutsiders.com/extra-points/2012/officiating-forward-progress-vs-out-bounds
Why is Leslie Frazier waving his arms like a madman?
MIN 20 at DET 13, Lions' third-and-12 from DET 37, :09 fourth quarter
M.Stafford pass short right to B.Pettigrew pushed ob at DET 44 for 6 yards.
Ultimately this play didn't affect the end of the game, but it highlights an important concept for spotting and clock management. Brandon Pettigrew catches the ball and runs forward for a yard
before being hit by Chris Cook backward by a yard and out of bounds. The wing official moves up to the spot where progress ended, and kills the clock. Immediately thereafter, Leslie Frazier is seen running up and down the sidelines giving a "run the clock" signal and shouting at the officials.
Frazier was correct. Pettigrew's forward progress ended at the Detroit 44-yard line. Subsequent force by Cook knocked him backward and out of bounds. By spotting the ball at the 44-yard line and killing the clock, the official gave the Lions the benefit of forward progress (the favorable spot) without the drawback (a running clock after a dead ball in-bounds) and vice-versa for the out-of-bounds spot.
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Refs should have reviewed it though and explained it.