The answer lies in the . PES 2015 was the debut of Konami's then-new engine, offering smooth animations and a slightly more arcade-like, responsive feel compared to the slower, heavier gameplay of PES 2017-2020.
Some modders create "back-port" patches. For instance, there are paid and free patches that update the 2015 rosters to reflect later seasons (like the 2021 or 2025 seasons) by updating faces, kits, and stadium textures. pes 2015 bal editor 2021