Haddin is averaging 15 in 2014, so if a replacement could bat well you have a lot of leeway for runs lost to poor glovework
But that isn't the relevant comparison.
If we choose to drop Haddin it's a comparison between Hartley, Ludemann, Nevill, Wade and Whiteman.
Wade is the best bat of the lot but is he that far ahead of Nevill to make up for Nevill's superior keeping?