My theory is that it is in his head.

Coming so close behind Ogier he surely must have expected to have big title chances.
Tried to attack too hard early which cost a lot of points.
Rovanpera rose up and suddenly Evans is permanently on back foot.

Car might be a factor though. As Evans wasn't very good with pre 2017 cars without active diffs so the diff changes for Rally1 might be particularly hurting him.