Yeah, I've seen this three or four times and done slow-mo replays. What's strange is that they break out and away from the route after the ball has clearly been thrown and when they were in a position to see that based on their facing the quarterback. And there were no competing vertical routes.
It's literally the only bogus thing I've seen that reminds me of the days when All Madden was synonymous with ridiculous cheese, rather than simply being a more difficult but realistic game play experience.