Brown was a very good slot corner that consistently beat out Jourdan Lewis. Lewis was only elevated when Brown moved outside. Brown’s biggest liability on the outside was ball awareness. He could stick to the receiver like glue, but receivers still caught the ball over the top of him because he wasn’t often aware of where the ball might be.
If the 49ers move Brown back inside, he is still an above average slot corner in the NFL, if, and this is a big if, he hasn’t lost any speed or mobility because of his Achilles injury. At the very least, he can be a quality backup for all three CB positions in case someone gets injured.
I never understood the lack of appreciation by some fans for Brown. He was always a quality DB, even if he wasn’t a top tier player. If his Achilles tendon his truly healed up, this is a quality signing by the Niners for depth in the defensive secondary.