These are the main points - to me - that would keep me from pulling the trigger.
I'm pretty high on Mallex compared to some, but he's a substantial downgrade from Inciarte. No, Albies isn't here "yet", but Jace is a considerable downgrade from him as well. Your point about the anticipation and expectations for guys like Wisler and Blair and the fact that they fell short should (again JMO) make the brass even more hesitant to go "all-in" just yet.
Again, I'm far from unwilling to part with serious talent. If something like Newcomb/Wisler or Blair/Mallex/Demeritte or Riley gets it done, I wouldn't bat an eye. I'm just not willing to back the truck up for for 3 years of Chris Sale when we don't have "sure things" that will produce at 2B, 3B, and behind the plate. If that package isn't enough for Sale, tell them they can have it for Quintana or offer a little different version of it to Tampa Bay for Archer.
I'm just not sold enough on Sale with all his question marks - size, durability, and makeup after his blow up last summer - to mortgage the future for him when we still have as many question marks as we do.