1. The OL gives the protection.
2. Case climbs the pocket, and makes a clutch throw.
3. Diggs goes high to make the catch (knowing he may get pulverized).
4. Diggs turns & looks down field instead of immediately going out of bounds (as most everyone watching expected).
5 Diggs takes the chance, and takes off down the sideline. He did not immediately know that he could not be caught from behind. He didn't glance back until around the 23 yard line. IF he HAD gotten caught from behind, and time ran out, and the Vikes lose by 1....., he'd be the one everyone was down on (just like they are now with Williams).
Might luck have been involved. um, I guess so. But not more than many other plays. You never know how that funny shaped ball is going to bounce.
Did Williams screw up. You're dog-on right he did. Can't clean that one up.
But lets not forget all the things the Vikings did right.