Return of Stump the Chump

[The Roamin' Umpire]

From last night's monthly off-season rules bull session:

K 4/8 @ K40. The booming punt is deeper than the returner R80 expects, and he catches it over his shoulder at the R4 while running towards his own goal line. His momentum takes him into his end zone, where he turns and starts to run out. He is hit by K62 before exiting the end zone and fumbles. The ball fires back into the field of play and is eventually recovered by R92 at the R6. While the ball was loose, R80 blocked K18 below the waist, likely preventing him from recovering the ball.

Your call?