Yep, Sanji took a huge L this chapter but realistically, he can easily regen from this kind of damage (just like against Queen) and he neither used DJ nor IJ.
I don't think that Sanji is completely helpless against a single Seraphim in this arc, how would it looks like? Sanji always getting his ass beaten whenever he fights someone? If they also switch between flame and speed mode, we will see whether Sanji has the ability to deal with one Seraphim.
Needless to say, Sanji got pretty wasted by one Seraphim...