Who do you put above him, then? I saw your thoughts about this earlier in the thread and you seem to be on board with Burgess and Shiryu taking the top two spots; I could see any of the Level 6 recruits staking a claim, even Devon (since we know little about her DF powers), but Augur’s been around a lot longer and, by your own admission, would be powerful enough to kill another presumptive high ranking YC, so why would that preclude him from being one of Teach’s top 3?
Auger could be the YC3 from one perspective- sniping- but in a more regular fight be significantly weaker than the other YC's. Much like Usopp.
The problem is this "YC3" designation. Yasopp is Shanks' YC3. I think this then makes people think he can go toe to toe with Jack or Cracker. I don't think that's the case at all. Yasopp and Auger, much like Usopp, will have one area they completely excel in, but aren't really "real" fighters. If anything, they should try and be as far away from their opponent as possible.
So, I can see in series Auger being considered Blackbeard's third. Much like I can see Usopp being considered Luffy's third, as much as it pains me because of what it would mean for Jinbei- no offence to Usopp, who I also love, but Jinbei is my man.
But if we were then to put these characters in the arena, they'd lose most fights unless we're to give them a massive advantage of being like an island away from their opponent, who is unaware of them. Because that's simply how a sniper really excels.