Stoll has this guy dead to rights:
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Runs right by him instead. This guy shouldn't be there if Stoll blocks him:
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Hixson does get to #18, so if that guy is blocked it's Washington 1 on 1 with #25, which is great. Although looking again, #25 makes a mockery of Woodyard's block attempt (probably why he hasn't been on the field), so maybe #6 is supposed to be the one guy for Washington to beat. And there is a ton of room in the middle.
But to your point, screens have not been good all year. Maybe Frost was thinking Minnesota wouldn't expect it because of that, but seeing the ones in the game it is a call that leaves room for criticism. I just don't know if the 4th down call is a drive blown by bad playcalling. We're in 4th and 2 because of bad blocking on 1st down, a receiver tripping on 2nd, and a a lack of power from Washington on 3rd. Those are also factors in the failed drive.