Are any players listed on the DL yet?
I think you can't officially have a player on the DL until the season starts and that's probably how Yahoo and other fantasy leagues run it. There will be a nice free agent run once everyone's injured players show up on the DL, probably Sunday.
Edit: Scratch that, Yahoo has a number of players listed on the DL already. Hmm, beats me then.
If you're a battery, you're either working or you're dead....