I understand what some are saying about the Lawday vs Chisholm thing, in that Chis would probably have a much greater impact as a sub than Lawday would. However, he is clearly the better player, and so really should be starting. If we can't impose ourselves on them for the first half, then I don't think impact subs will be enough. I just can't see Exeter letting us get back into a game if we give them a healthy lead.
I really do think that the key to this game will be discipline. Don't give them easy field position, even if it means long defensive sets and no competing at the breakdown.