I'm going to make an unnecessarily long post to explain this, since i've been asked this like 3 times so far.
All of the pages you guys questioned have calculations or scaling to justify their statistics.
Fujitora -> 6-B Environmental Destruction via Meteorites, High 6-C stats for laying the smackdown on Law, and being comparable to Doflamingo.
Doflamingo -> High 6-C because of his threads being strong enough to apply such energy against Fujitora's largest meteorite, and being capable of fighting characters who are strong enough to bust his threads, even when infused with haki (it's been agreed that his Awakened threads at least are = or possibly > to his Bird Cage threads, especially when we factor in haki).
Luffy -> Base, 2nd, and Gear 3rd are practically the same stat-wise at this point, and it would only make his Dressrosa and Wholecake descriptions twice as long if we included Gear 2nd and 3rd, and amount to nothing considering that the stats are literally the same. He's taken hits from Doflamingo, and broke his threads even while in base and could hard Doflamingo himself, even if the best thing he's done was make Doflamingo hack up some blood. He also managed to hold his own against Fujitora, and took a hit from him with nothing to show for it.
The stats on his page clearly say:
Tier: Likely High 6-C in Base, higher with gears, at least High 6-C with Gear 4th | Likely High 6-C in base, at least High 6-C with Gear 4th
I don't remember if I included "higher with gears" but even so, that doesn't mean "Low 6-B" with gears. "higher" is often used to suggest a character is stronger than placed.
For example: Luffy in Base has to be at the very least High 6-C in Base since he is strong enough to harm the likes of Doflamingo, who is high-up in that tier, otherwise it would make little sense by a plot-standpoint. in his Gears, we already know that his attacks are bolstered to some degree.
Gear 4th is something we saw actually lay the smack-down on Doflamingo's durability, and his thread durability, so we could already scale that DIRECTLY to Doflamingo's stats. Base Luffy could also hurt Doflamingo some-what, so he's listed as "Likely High 6-C" for that simple fact.
Does this make sense? I may have seemed very confusing at some point because I woke up 30 minutes ago and finished a phone-call.