Im pretty sure I started w/ one of the early updated rosters and just rolled with it. I've edited some players, ie. Dak and other Qbs that had really low ratings to start, mainly just the teams I was facing next on the schedule.
I know rosters are important not only for ratings reasons but also in getting the roster that has the player's you want on them, practice squad players included.
With player editing being available that also helps, especially if you think the draft picks are rated too high to start.
Another thing, Qb edits and qb traits can make all the difference in making or breaking the CPU gameplay.