Johnson was one of the eleven Chiefs players signed as undrafted college free agents in late April. Nothing really of note happened until a few days ago when he was seen walking after practice with an ice pack on his leg. Joel said nothing noticeable happened in practice that would indicate Johnson was injured. Maybe a pulled muscle or something is my guess.
Dan Santucci is a fourth year NFL playerr, who spent all of last season in Cincinnati on the injured reserve list due to foot and ankle issues. His main position is center but he can also play guard, which makes this move easy. The Chiefs have Casey Wiegmann and Rudy Niswanger competing at the center position currently. But recent injuries to to the Chiefs' guards have left the team just in need of bodies to take the field.
Santucci's addition also makes sense when you learn where he went to college - Notre Dame. Charlie Weis is bringing his troops along with him.
This is a minor signing and nothing to analyze too much. Expect more of these to happen as we move along this offseason.