I think there are multiple reasons that Dani played well last season.
1. Messi moved to RW, therefore more close to him. Dani and Leo always show a lot of chemistry.
2. Rakitic helped him a lot, especially defensively. Dani needs more freedom to play well.
3. The whole team played counter-attacks much more often. Dani is surprisingly good at initiating a counter-attack.
4. Suarez played as No.9 so that he did have one more target when he played long balls...