He wasn't eaten alive defensively. He put up 40 points, managing to put up good offensive numbers with tough minutes, that is actually good performance, not bad. If he plays the same type of minutes this year then he should do even better points-wise. What's wrong with that? He was drafted as a shutdown/defensive centre, I don't see what's boggling your mind with that.
Okay, he had a drought. But he had a great finish to the end of the year and that's going to make him a better player next season. I would be complaining at the beginning of the season, but now, the season is over. Horvat has experience playing those tough minutes, he'll be better going forward with those same minutes. I'm not sure if you have any stats regardless backing up "eaten alive defensively." Anybody can yell whatever they want, but stats would help your point.
Bo Horvat played tough minutes at the end of his rookie season and he continued it into last season. It's going to make him a better player and I think we were going to be a playoff team until Sutter got injured. When Sutter got injured, Horvat was responsible of secondary scoring and defensive minutes.