In the first half the play clock was just behind the game clock (e.g. 10 seconds vs 2:09) so you can let it run down 2:00 for the warning.
In this half the play clock was just ahead of the game clock (e.g. 9 seconds vs 2:10) so play clock would have hit 0 at 2:01 for delay of game.
Which is why Detroit had to run the play. It's not particle physics.