How strong are the Scabbards?

[SSJ2]

I just noticed this quote. We know that Ulti was around G3 Luffy's level, and supposedly the Flying 6 aren't even strong enough to beat the Scabbards when "mortally wounded". So clearly they are in between G3 and G4, but where do you think that would be?

Also doesn't this sow doubt in the fact that the Flying 6 we're confident in being able to beat Kaido's Calamities? Where is this confidence coming from if they are dramatically weaker?

 

[Future Warrior]

The members power encompasses a pretty wide range. Sulong Dogstorm and Catviper are pretty well Yonko Commander level while someone like Kinemon is more comparable to Brook.