Doffy was playing around with both Law and G2/G3 Luffy until the Gamma Knife happened and he started to struggle a bit even against the latter by then
Tbh, can we still use this as an argument? Jack is facing 100 sulong minks and defeated lots of them. During Zou, none of them could even injure Jack, Inu and Neko, comparable to Law, even weren't enough.
But if Jack manages to defeat two of them at once despite their sulong forms, even if it's an extreme diff fight, I really would reconsider that "Doffy destroyed Law and G2/G3 Luffy" argument.
Only Doffy's portrayal as a top warlord would save him. But tbh, Jack is impressive even for YC standards.