On a Cal defensive unit with nowhere to go but up, sophomore Griffin Piatt is starting to distinguish himself at the safety position after playing receiver in 2013. Piatt (pronounced pie-at) played both positions at Campolindo High in Moraga and brings a ball-hawking mentality to safety. Piatt, who was redshirted in his first season at Cal in 2012, lost 2013 to a knee injury. Another productive practice in full pads with live tackling Saturday could go a long way toward helping him carve out a place on a depth chart that will be released next week. Redshirt freshman Darius Allensworth is, like Piatt, making the most of spring drills. The head coach's father, the legendary Spike Dykes, was at practice, wearing a Cal windbreaker.