Doflamingo benefited from getting to 2v1 Law along with Fujitora for a while. By the time Law got to fight him in a 1v1, he was already tired and injured, and it was explained in the same arc that the effectiveness of his ability was dependent on his stamina.
Yes, I’m sure Vergo felt the need to hold his heart hostage because he was overconfident and thought he could easily thrash Law. You missed the whole point of Law’s speech to Doflamingo when he OSed Vergo.
You’d have a stronger case if you argued Law is a bad matchup for Vergo, which I think isn’t inaccurate.
If you’re talking about Law, I disagree about him being below Jinbe. I have Jinbe at YC3 level and that’s pretty much where I put PH Law. And it’s not just Law’s haki that was a problem, it was the combination of his haki and power.
But if WW level still seems too high for you, you can instead place Vergo around Sasaki’s level. TRs aren’t equal, there’s a clear hierarchy between them. You have Page One and Ulti in the low tier category, Sasaki and Black Maria in mid tier and WW at the top of the list.