While your math is correct you're missing the fact that going from a standing start in full pads is going to be a lot slower than firing out of starting blocks in shorts and a t-shirt. What's important to note is that all the other players on the field could NOT cover that same ground in that amount of time.
This. Watch the play carefully. Overshown has coverage responsibility 1st.
Watson rolls right trailing the receiver and mirroring Watson but pressure & his coverage is good.
So he sees his receiver turn his head and lose contact with Watson's eyes: the area has become congested with WR/DB population and the sideline boundary.
Then he instinctively commits to Watson, believing his speed to the QB can beat the next window of opportunity for his cover to appear available to the QB.
And he was right.
That's a play you cannot teach folks. That is elite ability.