The Bengals have neglected their need at safety for a long time and at the end of the 2011 season it caught up with them. While Reggie Nelson got his career back on track in 2011, strong safety Chris Crocker got worse and worse, which was highlighted by a terrible game against the Houston Texans. After guard, cornerback and running back, safety is a big need for the team, but unlike the guard, cornerback and running back positions, this year's draft class isn't necessarily extremely deep with safety talent.
In the case of Nakamura and Zbikowski, it will be more about opportunity than money. The two safeties have been solid when they have gotten chances and I'd suspect that there will be interested teams willing to offer decent contracts and more playing time. Already, I've seen or heard reports that the Indianapolis Colts, Tennessee Titans and Cincinnati Bengals could have some interest in Nakamura.
Nakamura was a sixth-round pick in the 2008 NFL draft out of the University of Cincinnati and has been a backup safety and a special teams player for the Ravens in his four years with Baltimore. His stats don't stand out as being incredibly outstanding and ESPN In$ider's scouting report grades him at 56 out of 100 (Chris Crocker has a grade of 66).
Nakamura may not have been given a chance to start for a team and could be a great player in the future, or he could be a career backup. I doubt he's the long-term answer for the Bengals in the future but it's nice to know that the team may be looking to upgrade the position when free agency opens on March 13.