Fact Form Manga is That Soldier That Eat Failure Smile (Pleasures) Are Stronger Than Normal Soldier That Didn't Eat Simile not Only Failure Smile wont Nerf Any One but it's Also Power Up (To Some Degree)
Oda Clearly Ranked Them Twice
First Time in Udon Prison
in CH 936 Queen First Send Waiters and Luffy Knock Them Out With CoC Easily
in CH937 Queen Send Pleasures To Fight Luffy and Luffy Beat Them Up by Force
Then He Send Gifters
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Also In Recent Chapter Queen Called all BP Ranked and Again We Can see that Gifters are Higher than Waiters
Was Killer Nerfed Because of Smile? Definitely no
Was Killer Nerfed Because of Torture? Maybe But Base of What Hawkins Said in CH954 it seems that He Wasn't Tortured
he wasn't in right Mind? Maybe But also Hawkins Didn't recognized Zoro and Called him ZoroJuru Like Killer After he see Luffy Then he Recognized Them
he didn't Have His Usual Weapon So he Was Nerfed? Possibly You Can Make argument For Both Side Personally i think he Could Fight better With his Normal Weapon
Personally i think Killer Was Nerfed But Zoro Also was Nerfed and it Was 2V1 and Match was in Killer Favor
if both of them wasnt nerfed personally i think Zoro Would Win Mid Diff With Out using 3000World,1080p and Asura
also i don't think Killer is Any thing more than Mid Diff For RS Sanji and Jinbe