Griffin is fast. But Darrell would catch him. It might take the whole length of the field though.
You bring up a very important variable, that we all seem to have overlooked, in addition to some other variables.
It's not as cut and dry, as a race from start to finish.
So, when you're talking about whether someone catches someone from behind, you
have to consider and specify :
1) How far Green would have been behind Griffin when he began pursuit
2) How far away from the goal line Griffin was, when Green began pursuit.
3) Whether Green would have had a "straight line" towards Griffin, and no blockers to complicate the route.
4) Whether there would be a dirty player like Andre "Dirty" Waters who laid a cheap shot on Darrell to knock him out of the play.