This is not the problem. The problem is that Luffy's portrayal since the timeskip seems just too bad compared to Law. The strongest opponent he defeated is now getting wrecked by Lao G who isn't even seat level and it seems even the Doffy he is supposed to beat by the end of the arc will be heavily injured or something. When will he have a full fight against a strong opponent for once? On the other side, Law defeated a seat in one slash(Vergo), clashed with an admiral and Doffy and will do the major job against Doffy while injured. What type of portrayal is this?
And on top of that, Chinjao this time has his drill head too.
I have a feeling that Luffy will be making a comeback settling the powerlevels, because by current portrayal, it seems that it would go to High diff for him if he were to fight even seat holder/opponent of that level(which law did and some others are gonna do).
For the seat stuff. In vergo's case, I'd say that it Was difficult for law to put him down since he had to use probably the largest slash he could. So in a sense, it wasn't really easy for law since he had to use a very strong move. It's the same as if luffy decides to go elephant gattling on vergo/pica from the very start and defeat them then and there. We would say Luffy just defeated a seat in one move yes, but the technique used also needs to be considered.
Though him fighting while being injured, that surely gives him a better portrayal than luffy.