Also Monday, the Chargers signed wide receiver Demetrius Byrd, their seventh-round pick in April’s draft, to a four-year contract. In addition to the two additions, the Chargers also made three subtractions Monday. The team waived wide receiver Greg Carr, offensive tackle Dan Gay and wide receiver Rodgeriques Smith. All three players joined the Chargers as undrafted free agents in April. With the moves, the Chargers’ roster currently stands at 78 players. They have make three more transactions by Tuesday at 1 pm in order to reach the NFL-mandated limit of 75 players.