Statements or no statements(which doesn’t help Mingo regardless), we've always had a direct comparison. Katakuri, Cracker and Mingo all fought the same guy within a week and all 3 have the same style of keeping the opponent away while avoiding hits.
Mingo by far is in last seeing how he can only stalemate Boundman, and it was Boundman that broke the stalemate by avoiding Mingo's best and getting hits in. Cracker easily held off Boundman and cut it's cheek without issue. He was in complete control. Katakuri goes without saying. Mingo needs G4 to wear off to win(aka he can't beat Boundman) while Cracker and Katakuri can win without the time limit.
Not only that but we also have a Luffy who was stronger when he face Cracker and Katakuri(he even got a powerup with FS). So the Luffy who face Cracker was stronger than the one who face Doflamingo, meanwhile the Luffy against Katakuri was even far stronger than the one who faced Cracker.
Luffy(Katakuri lvl)>>Luffy(Cracker)>Luffy(Doflamingo).
So not only that Cracker got a statment who clearly implied that he is stronger then Doflamingo(why Big mom would send someone weaker than Doflamingo? Oda put this statement for a reason, to show that someone come for Luffy ass who was stronger than Doflamingo), but also Cracker fought a stronger Luffy version.
And he low diffed G2/G3 worse as what Doffy did. Against Boundman, Cracker was equal or even had a slighty upperhand, his haki was very impressive meanwhile Doffy haki is.... legit trash... Cracker was able to fight Boundman back, Doffy was clearly under that lvl, Oda show a growing of Luffy power based on facing stronger opponents. Doffy couldn't even damaged G4, hell his haki+awakening was weak to even cut base Luffy haki...
It is clear where we place Doffy around the ranking, behind Cracker, slighty above Perospero. Katakuri can legit low-mid diff Doffy. Same counts for King, while Queen/Cracker beats him high-extrem diff.
Katakuri>Queen>Cracker>Doflamingo=> Perospero/Jinbe>Snack=>WsW.