Doesn't look to me like Erskine has anything approaching 90 mins in him. Can start him if you like but, when you need to have a sub in place just for him, it's more than likely that Chris will find his way back onto the bench at kick off.
Without Corcoran we definitely need, or at least could do with, more width in the team. Signing an attacking right sided midfielder would help and maybe then Erskine could hold a place down the left in a 4-4-2. Got a feeling tho' we'll be back to either a 3-5-2 with wingbacks or a narrow makeshift 4-4-2 with central midfielders (Cairney, Hodge, MacBeth) being pushed out a bit. Don't really see where Erskine would fit in other than as an impact player. Hope I'm wrong and he improves as he is indeed the type of player to excite the crowd.