As a longtime Show player, rosters will work themselves out. Remember that the game released before the season, so 40 man rosters weren't even established then, let alone 25. Roster updates happen frequently. It's advisable to run some sim franchises until a roster comes out that you like.
As for playing since 21, you should know that franchise used to be a much fuller experience. Not only have they neglected it the past several years, before that they stripped away all the owner mode stuff that used to be in it. Now they took away year-to-year saves.
It's shameful how dismissive SDS is of franchise mode and its fans. Morale for devs working in franchise -- but honestly, what do they DO?! -- has to be so low...