We need squad players and Perch is certainly versatile to cover both left and right back positions. As to what he offers more than Furlong, perhaps the clue is that Furlong is young and is still developing, and currently needs regular competitive game time (thus the loan) with the objective is to become a regular first team player, rather than squad player. Unfortunately, we will have to wait and see how this develops in reality.
Faultless logic, agree. Also I think we need to give players a chance, having seen ( accept only 3 games) the impact JFH is having on the likes of Caulker and BFG, perhaps Perch can improve over last season. A versatile defensive squad player will always be needed.