The most overrated Baltimore Raven of all-time is Anquan Boldin.
Before all your senses are drowned in outrage, take a second and think about it. Boldin's best and most memorable moments came in the 2012 post season. The problem is not related to Boldin being an overrated player, when talking about his skills, but more so when related to the insane amount of backlash when the Ravens traded him.
The fanbase lost it's mind. Outsiders thought the front office had gone crazy. Anquan Boldin was not Calvin Johnson though, even if you would have thought it from the reactions.