This might not be a popular reply, but i have to give team A some credit. We all can learn from his strategy. One of th e best insurance options a top team in the running can buy is that "homer" guy like Ortiz. Any good fantasy baller worth his salt knows what every favorite team his competition is routing for. Once you solidify a good footing in the standings make sure you get that one player that is the face of your leaguemate's favorite team. Once his is eliminated from the playoff running you must strike.
Some may call this strategy sneaky, unethical, or even collisional. I don't. This is a chess game fellas. Always play with one eye on the end game and the other on the prize. Manager A gets some insurance for his final run, and the other gets to enjoy the rest of the season watching his favorite player even though he is out of it.
If I havent convinced you yet then here is what you should do next year. If your league primarily holds together year to year then make the winner of the consolation loser bracket (7th place after the playoffs) get awarded the first overall pick next year. This way the bottom feeders will still have something to play for even though they wont win the championship.
In one of my leagues we have the 7th-12th place teams be awarded the top 6 draft positions. The condition: They have to earn it. This will eliminate a lot of these dumb trades.
I hope this helped.
Be the change you want to see in this world.