is it h2h or points???
If teams have the same Win-Loss record after the end of the regular season, then it typically comes down to points scored, but it may be different in each league depending on the settings. Check with your league settings and Yahoo Help on that.
Look it up. It's division record, then total pts.
ChrisM is right, go to Yahoo help and search for "tiebreakers". There is a chance for a 3 way tie in one division in my league so I had to look it up tonight.
I believe it goes by total fantasy points and then if that is also a tie, moves to which team scored the most points in the most recent week