Honestly, the main reason why it looks like older stats have more importance is because we needed some time to properly understand how new stats work. Old stats have been there for 10+ years, most people here and most mods are familiar with them since PES 6 and before. There's a combination of knowledge and comfort regarding the way we rate these stats that makes them way easier to rate and this is why they're somehow prevalent. Being familiar with the scale helps too; IMO there's an obvious lack of synchronisation regarding the scale of the newer stats accross the different leagues, but it's just a question of time really.
Konami really didn't help with that. Their explanation for player attributes don't help at all when they're not non-existent, and since 2011, PES went through a tough transition during which Konami did a fuckload of questionable tinkering with both the stats and the game engine. The result of that was a few very average games (PES 12 and 14 mostly) and they only really started to settle with PES 16 IMO. PES 15 had the core of what PES currently is today but was a very unrefined game.
The stats system went through the same problem and I think most, if not all stat makers had issues getting familiar with these changes. Stats being added, stats names being changed, stats being removed and being roughly emulated through other stats and player cards. The system is still a mess, and though I believe we're slowly getting there, it's hard to settle on it since Konami changes the rulebook every year.
It's true there are a lot of inconsistencies due to how we implemented new stats in the DB, but sticking to suggestions in these player's threads would be a good start. Mods do read and do listen to suggestions; do not mistake lack of responsiveness for a lack of consideration. Feel free to suggest and post when you think something is wrong or inconsistent regarding a player's set. The effort is and will be appreciated anyway.
Everyone knew it was impossible. Then came along a fool who didn't know it, and he did it.