SANTA CLARA, Calif. -- The San Francisco 49ers brought a whopping 56 tryout players to last weekend's rookie minicamp. It made for a crowded gathering in which the Niners nearly had a full 90-man roster on the field.

But there was a method to coach Kyle Shanahan and general manager John Lynch's madness. Nobody knows better than Shanahan the type of talent that can be uncovered in such settings.

In previous stops as an assistant, Shanahan was on a staff that identified players such as receiver Taylor Gabriel, cornerback K'Waun Williams and receiver Brandon Banks as tryout players who eventually not only made a 53-man roster but became contributors. Gabriel is the most famous of that group, becoming a star for Shanahan in Atlanta last year after the pair first worked together in Cleveland. The 49ers signed Williams as a free agent this offseason.

The Niners announced Monday the signing of three players who participated on a tryout basis at last weekend's rookie minicamp. They added safety Chanceller James, receiver BJ Johnson III and offensive lineman Richard Levy, while releasing running back DuJuan Harris, receiver KD Cannon and offensive lineman Bret Treadway to make room.

Here's a look at the three players the Niners signed:

Chanceller James, safety, Boise State: James played in 35 games with 24 starts for the Broncos, posting 171 tackles, 10.5 tackles for loss, four interceptions and three sacks. Better suited as a strong safety who can play square to the line of scrimmage but should get an opportunity to prove himself in a secondary that is still figuring out where the pieces best fit.

BJ Johnson III, wide receiver, Georgia Southern: The 6-foot-1, 210-pound Johnson played in 44 games with 35 starts. He had 92 catches for 1,377 yards and six touchdowns in his college career. The Niners have room for a receiver to force his way on to the roster, though Johnson will likely need to show he can contribute on special teams in order to be seriously in the mix.

Richard Levy, offensive lineman, Connecticut: Levy started 37 games on the offensive line for the Huskies, including all 12 as a senior. He was a two-year starter at left tackle but also played guard, giving him the versatility that will be required for him to have a chance to crack the roster. The Niners have room for offensive linemen capable of playing multiple spots to provide some depth, though it will clearly be an uphill climb for Levy.