And if Asamoah is injured, we have to field either Peluso or De Ceglie on the LWB. That's not really better, is it?

In fact, I'd say it's worse since you forgot Caceres four our defense. Another difference is that Coentrao would go directly into our starting line-up (yes, Zach) while Ogbonna is "only" a back-up.
I'm still happy for the purchase of Ogbonna, but I'd definitely choose Peluso over him.