If Jordan Crawford continues to protect the ball and shoot like he has been, the solution is in-house.
Dion Waiters is a few years away from being more useful than Crawford or Bradley. Right now, he is a net minus with a lot of promise.
Dominant 2-guards are rare birds. Many of the best ones right now, like Butler, Green, Iguodala, Sefolosha, are 3+D heavy players, and not creators like Harden, Kobe, or Wade. Courtney Lee actually holds his own when compared to that first group.
What we really need in order to be a contender is a guard or a small forward who can get a good shot, when required, one-on-one. Late in games when the referees swallow their whistles, defenses hold like crazy off the ball and brutalize post-up players. Crawford is presently our best answer for that, but he's definitely not the go-to option that Paul Pierce was.