Nami and Usopp are gadget fighters. They could beat Buffalo and Baby 5 with them, but if unarmed, they'll lose to Arlong. Don Krieg would be a gadget fighter, but without his weapons, he's still a formidable foe for an East Blue scrub.
> The Numbers were mentioned after the Tobi Roppo in the roll call.
This is much less important than the Tobi Roppo being a rank superior to the rank Haccha (a number has). That being made a Tobi Roppo would be a promotion for Haccha denunks any notion that Numbers are comparable to or above the Tobi Roppo in rank.
The problem with your "admiral striking strength = Kong Gun + Injection Shot" theory is that the scene implies Injection Shot has comparable striking strength to Kong Gun, and that's obviously false. Law is not as much a physical monster as Base Luffy let alone Boundman Luffy.
@Noctis on some other forum.
User: "Didn't you think Ace's death in One Piece is sad?"
Noctis: "I don't know. I don't watch or read One Piece."
User: [Link to Ace's death.]
Noctis: "My condolences to that strange anime character."