Okay.
I'm not convinced a great RB would help Krasic that much, other than meaning he should have less defending to do.
In many cases I think that when a team has a good attacking winger, such as Krasic, having an attacking fullback playing on the same side only serves to create more traffic on that side of the pitch and is likely to result in the winger having less space in which to work.
Better, in my view, to use other players to stretch the pitch to force the opposition to spread all over the pitch and not be able to commit several players to marking the winger.
Pirlo signing should help Krasic a lot, though.