Mattock played more than half the games at left back and only missed out on the others through injury.
Maghoma must have played 30+ games this year.
Zayatte was a handy back up that would've played more without injury and so equally needs to be replaced.
Coke played an odd amount of games at the start of the season (wiki says 16)
These need to be replaced and we at least need some more squad players for when injuries hit. We wouldn't have let 11 players go if we weren't going to improve on them. We may not buy 11 amazing players but we should be aiming for at least 11 squad improvements that will include the right calibre of player needed for promotion in the next couple of seasons.