The Ravens also plan to cut undrafted rookie defensive tackle A.J. Patiali’i and hope to sign him to their practice squad, according to a source.
Stephens was on the Ravens' practice squad last season. A 2010 Cincinnati Bengals seventh-round draft pick, he previously played with the Chicago Bears and Buffalo Bills. He played college football at Iowa State.
Roberts played at Tennessee-Martin where he had 53 tackles, including 11 for a loss, four sacks and a forced fumble last season. He finished his career with 12.5 sacks.
He played defensive end in college, but the 6-foot-2, 252 pound Roberts converted to outside linebacker in the Ravens' 3-4 defense.
Overbay was with the Houston Texans previously and also had stints with the Detroit Lions, Tampa Bay Buccaneers and Miami Dolphins. The 6-foot-5, 270-pound tight end from Eastern Washington hasn't played in a regular-season NFL game.
Hopkins, who played at Virginia Tech, got the highest signing bonus -- $10,000 -- among Ravens undrafted rookies.
The 6-foot, 321-pound tackle had 165 career tackles, 13 sacks, 25.5 tackles for a loss, two forced fumbles and three fumble recoveries in his college career. He was a second-team All-Atlantic Coast Conference selection as a senior.
The Ravens have until Saturday at 4 p.m. to get down to the NFL roster limit of 53 players.
The Ravens are now at 70 players, but don't have to cut 17 players to get down to 53 players because running back Ray Rice (personal conduct policy suspension, two games) and safety Will Hill (substance-abuse policy suspension, six games) will be placed on the reserve-suspended list. Meanwhile, nose tackle Terrence Cody (hip surgery) can be placed on the reserve-physically unable to perform list. Under that scenario, Cody would be required to miss the first six games.
Rice, Hill and Cody won't count against the active roster once those transactions are processed.