A day after the Ravens agreed to terms with three of their 2012 draft picks -- amid a flurry of Ravens news -- they hammered out a deal with another on Wednesday morning. Delaware center/guard Gino Gradkowski, one of the team’s two fourth-round picks, has agreed to terms, according to a league source.

The 6-foot-3, 300-pound interior lineman will start off at guard, but the Ravens hope to move him to center whenever veteran center Matt Birk retires. Birk signed a three-year deal this offseason, and he told us Monday that he is looking forward to mentoring Gradkowski, with whom he shares an agent.

Gradkowski is the fourth Ravens draft pick to sign, following offensive lineman Kelechi Osemele (second round), safety Christian Thompson (fourth round), and cornerback Asa Jackson (fifth round).

There are now four picks left for the Ravens to sign, which is pretty much a formality. It is expected that all eight members of their draft class will be under contract for this weekend’s rookie minicamp.

Adam Caplan first reported the news on Twitter.