For the record, Alex, Ash actually did a LOT better in Kalos than in Unova. Heck, he even did better than in Sinnoh. He got Top 4 in Sinnoh, Kalos had him getting Top 2. Mathematically, that means he did better in the latter (and you can't dismiss mathematics as opinion). And I'd rather wait on Alola's ending before we decide what his progress in Alola will be. For all we know, he'll be the first champ of the Alola league (and we KNOW there will be a league since the professor was inspired to form it in Episode 43 in response to Misty and Brock's battles with his class).
I will agree with you on poor writing, though.