Rosters aren't completed because teams aren't actually set, plus this is only for MLB level at this point. So it would be premature. I know some roster makers like to do that, but I've never understood it. There are dozens of guys who are invited in right now who are going to be released. Besides, the way I did this was to import the completed teams to an existing stable roster, so there would be duplicates of players I'm sure.
If you can't wait for opening day, I believe there are "Winter" rosters in the DL section done by ARkey.