I'm pretty sure Talib and Peters play RCB and LCB rather than having them follow specific receivers from one side of the field to the other. As such Peters would cover #1 receivers when they lined up on his side whether Talib was in the game or not.
The difference in Peters' numbers is primarily due to playing press coverage vs off coverage although it seemed to me that Peters also gambled more with Talib out looking for ints and pick sixes, thinking he had to make up for Talib's absence by being 'that guy'. And he got burned a lot as a result.
AlbaNY_Ram