It's freaky to be on the bad end of such end-of-season drama, but that's why we're here...the unexpected. I'll often use the same players on different teams, with wildly different results. That's dice for ya. But don't quit on us. Just take some deep breathes and hang in there; your luck will turn. Your opponent is a quality manager who's been in a few of my leagues, and I respect him. He doesn't control HAL...no one does.
That is extreme to see such a negative run differential win the league, but the offered explanation makes a whole lot of sense. I'll try it with my next team. I've had MANY teams that finished second or even third despite a huge positive RD.
Perhaps dump the $25 leagues and downshift to the $12.50 leagues, where it might not hurt so much when the dice go berzerk. But let go of that season and have fun with this game. And remember it is just that...a game.
High regards to both parties...