Neko fought to a stalemate against a guy who is one of Kaidos top 3 calamities who has a 1 billion beri bounty, also Jack is being saved for a later time in the story indicating he is very strong and likely stronger than Doflamingo who was just defeated an arc ago. Luffy even sensed that a weakened inuarashi who was equal to Neko to be very strong, mind you the only other person Luffy sensed to be strong was Fujitora, an admiral. He also seems to be a veteran as inuarashi seemed to know Shanks, and the two seem to be on good terms, as he had nothing bad to say about Luffy wearing his hat.
Neko pre torture could have definitely been equal to or stronger than Doflamingo. But I expect him to be weaker with these injuries.