I think he did not fuck up untill he had problem in Turkey (wich we can not blame on Neuville).
If you look at results and pace the whole year Neuville was the only one always up there. In the beginning of the season al went easy to be top 3, end of season he had to push it to the limits to much to keep up whit top 3.

I personally feel the car started 2018 as the best, but in the end was third maybe even fourth fastest.
Whitout Turkey points lost third and fourth places in remaining rounds would have been enough for wdc.

I hope the team has done there work to improve the car on the short off season. Loeb coming in the team wil be very good for them on that part in 2019