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As Kirby stated, on third down if the offense is stopped for no gain they would have kicked the field goal. Since Stockton got within a yard of the 1st down the mindset was to go for it at that point. Since they were going 'hurry up' there was no time to swap Jones out (he's usually the 3rd down back I believe). The play was there, provided you get a decent block by the guard on the right side, Cash would have most likely made the 1st down and possibly scored. That didn't happen obviously.
I guess the catch with that nullification, though, is that (since the thought process was "if we get any yards, we're going for it") we would have gotten the down back, been pushed back five yards, taken another couple seconds off of the clock, and kicked the FG.