ESPN looked back on the history of free agency this week, and listed the worst contract for each team in the NFL. The article, Picking the worst-ever free-agent signing for all 32 NFL teams, chose one contract for each ,team, but the player had to be a free agent signee so Dennis Pitta would not be eligible for the Ravens.
The choice was cornerback Domonique Foxworth, the Ravens big free agent acquisition in 2009:
Cornerback Domonique Foxworth
A knee injury caused the Ravens' top free-agent signing in 2009 to never live up to his contract. Baltimore gave him $16.5 million in guaranteed money, and Foxworth delivered four interceptions and 18 games over three seasons. A close runner-up was offensive tackle Leon Searcy, who never played a down for Baltimore after receiving a $3 million signing bonus. He partially ruptured his triceps in his left arm in training camp and then reinjured it in practice two months later.
Foxworth was supposed to step in as the Ravens top cornerback with Chris McAlister no longer a Raven, but he was in and out of the lineup for the first few years of his contract before retiring. He barely played more than a full season of games over those 3 years, so I think it is safe to say he was a bust. The Ravens secondaries were still good for most of those years, despite his absence, with a solid group with Dawan Landry and Ed Reed in his prime at safety, and Chris Carr, Fabian Washington, Lardarius Webb and eventually Cary Williams at corner. So he might have given the Ravens little at for their money, but in the end it worked out pretty well, with 2011 being one of the best Ravens teams of all time.