There haven't been that many Janis throws to talk about, but maybe I'm missing the one under discussion. On that one, Janis was behind the DB, slowed down, and couldn't reach the football, which he could have done had he kept running. The ball wasn't underthrown, nor would he have had to shove the DB (actually, couldn't have, since the guy was behind him). He also didn't have to slow down, he actually shouldn't have.
Full disclosure - never played the game, am not an Xs and Ox guy, just honestly can't understand where this discussion is going.