The Baltimore Ravens field the best overall special teams units in the entire NFL. The only aspect where they could improve in the fifth phase is by adding a kick returner with the ability to provide a Jermaine Lewis or Jacoby Jones caliber impact.
The Ravens did recently re-sign Michael Campanaro, who is expected to compete with Kennan Reynolds for the primary return man job in training camp. Lardarius Webb and Danny Woodhead also have experience returning kicks, but both are probably too fragile at this point in their careers to play special teams full time.