Delaying of a car isn't anything to do with managing a driver. It was the reactions that came after that which seemed to cause all the problems.
People gave Matton a lot of crap for how he managed Meeke. He never said close to what Penasse said about Neuville last year.
http://www.maxrally.com/2015/08/26/n...thing-to-prove
I'm not sure how much the driver rotation with the 20 car really helped - especially with last year's very public "benching" of Neuville at the end of the season to 'give him his confidence back'. I think Hyundai also struggled with tensions between Neuville and Paddon. You can see their reluctance to favour drivers, and the fact they did the 10-round paperwork for Sordo this year, rather than being forced to pick between Hayden and Thierry, speaks volumes.
Ultimately I think Neuville was probably extremely difficult behind the scenes, and Hyundai's top brass reacted to it quite badly. No one is blameless. Probably the best thing is to go their separate ways.