What I've been noticing, (even on higher difficulty levels) during authentic gameplay, the AI CPU defenders still jog behind defenders and are still way too passive at closing you down. This leads to repetitive, easy through ball goals. This was an issue in 25 as well. I fear that EA just adjusted sliders without adjusting CPU AI to adapt to this new game speed. What happens is when the sprint speed slider is turned down, this makes AI defenders reaction speed slow down as well, leading to passive, delayed and overall poor reactions.
I've been testing and adjusting sliders for years and this does happen. Slowing down the speed in authentic mode is great, but this means AI defenders still need to be able to sprint in desperation, not jog lazily as they do when sprint speed is turned down.