I don't believe Eriksen is playing bad on purpose. Let's just be honest here, he's never been the type of a player who could pull the team out of shit when needed, you would expect him to score a free-kick or two from time to time but he never took on players, he never made that fantasy pass that'd make you think where the hell did he pull that from. So he was more like a "stats" player, you expected him to create some chances, maybe top the assists charts but that's it.
That being said, I think it could be the case where he's simply lost his touch. Some player just burn out. His peak was a few seasons ago and now maybe he's just regressing. If I was him I'd consider a move back to the likes of Ajax where he could regain his form a bit. Real Madrid or Barcelona would eat his soul alive.