Regardless of reasoning, the finishing position is a deliberate choice - otherwise why have two rounds of COTD battles after Trip when all they serve is to bump Ash's final spot up?
Assuming there's logic to it other than picking a number, Ash having a worse finishing position than the previous league can only mean one of two things, Ash didn't do as well at training for the league or the competition was much stronger. Otherwise consistent writing should mean that someone just as good doing the same thing again should achieve similar results.
They skipped two battles just to bump Ash up a rank. If they didn't care about his rank he could have come in the Top 16 again.
Also everytime a league ended, they would purposely have Brock state to the audience what rank Ash got. When Ash lost to Tobias, Brock said, "This is the first time Ash has made it to the Top 4," as if the writers wanted everyone to know that.
Granted I could see them rushing the Virgil battle into this ep, assuming Pikachu Vs. Lucario ends after the first 5 minutes. The Virgil match would be rushed like hell, but I wouldn't put it passed the writers.