It is close and I think your right that those two timed it perfectly.
The ineligible receiver no call is borderline, so I wouldn't fault the ref for calling it either way.
This holding was at least as bad as the call on Pay that negated the Miles Davis TD.
What is frustrating about the illegal block is that it would have never occurred if the play was blown dead. There is no excuse for why at least one ref swallowed their whistle.
Bad spots occur routinely in every game. This is probably the hardest thing to consistently do correctly as an official. However, this one was bad because the official marks it correctly, about a yard shy, but indicates the chains should move. Somehow before the next snap the ball was placed a full yard forward of the initial spot.
I am just a casual fan with no officiating experience, so take my observations for what they are worth. I would like to hear from experienced officials on how easy it is or isn't to spot the ball.