World number 58 is better than a World Cup/China Open/European champion. Sure thing. You must be smoking weed of low quality. It's totally a form thing. That said, Dima may never regain his form.
IF you mean Dima is the more accomplished player, sure. But this is not a matter of form.
Pucar's recent results have been strong enough to show that Dima is not losing on form in that matchup. It is entirely your prerogative to disagree. But Dima's form is entirely fine. If he had played a player other than Pucar, it would have been very obvious. Playing Pucar, it was just as obvious to me, but not to you.
Lin Yun Ju beat Dima in a handicap match 2 years ago I think. He has beaten Dima just about every time they have played. You can blame form. I would argue that Lin Yun Ju is just the better player in that matchup. You could point to world ranking and other stuff if you prefer.
If I want to do a slightly deeper analysis, Dima tends to overpower most European players. Against Asian players, this tends not to work as well because they are used to power. And in Pucar's case, his size means he has no deficit in power. So other things tend to matter.