I still believe he'll turn it around from where he's currently at, but I'm not so sure he'll ever be better than he was last season, which still isn't very good.
With the bat swing speed data that was just released, it shows that Ruiz is one of the slowest swingers in the game, which makes sense given the overall lack of power throughout his career. I don't think that part of his game will ever develop. Theoretically you could maybe see him turning into an Arraez/Kwan type, who also have some of the slowest bat swing speeds, but make up for it by having great bat to ball skills and hitting the ball on the sweet spot for soft liners over the infield and in front of the outfielders.
I think that's the best case scenario at this point.