FZD is an EJ just like most of us. Since 2013 the style of fan has been changed to a classic chinese forehand player. I think that the fan's style at 2013 china national games was way better than this one.
He used to play more with backhand and chiqita, and play closer to the table.
There is an old interview made by Dan, where he asked to Fan if he prefer backhand or forehand, Fan answered that he prefer backhand. While in a recent interview made by ITTF(I'm not sure) he said that he prefer forehand. So this mean that during the last years his own way of playing table tennis is changed. This Could explain why it is not as stable as before with its backhand
Actually not suprised he's complaining about his backhand, his backhand seemed very obviously in transition this tournament.
Both in singles and doubles, he's been playing these massive whipping backhands like he used to while younger. I think may people have remarked that he seems to play with less power than he used to a few years ago, especially on the backhand side where he's been using a shorter, quicker action for a while now (though still pretty powerful).
I'm honestly glad he's trying to capture some of that previous style, and frankly whatever he's using on the backhand now seems to be working with that stroke. I think he just needs to stick with what he's using now and just get more used to it, integrate the new/old backhand properly into his overall game again.