I think we can all agree that no PES or FIFA from PS3/XBOX360 gen onwards were made with the worst/lower-league teams in mind. I think not Konami nor EA really expect anyone to play with any team below 3 stars out of 5. That's why when you pick the lowest ranked teams you can adopt the same style of play as with a 3 or 4 stars one.
I agree, and I could accept that - because I'll be honest, now all the Premier League stadiums are in the game, I feel like I'm missing out playing anywhere else (lower league, or different country).
However - last night, all my testing was a 3-star team against a 4.5-star team (Qarabag v Liverpool), controlling an alternate team across 10+ games, on FIFA 16 (modded), 17 and 18. Not two rubbish lower-league teams.
I think the balance is better overall in FIFA 16 for sure, but as Qarabag (across the top three difficulties), I could control the game, and Liverpool couldn't score. When I swapped to control Liverpool, I didn't feel like I had a fitter, or stronger, or more talented team - I could get down the wings just as easily with either team.
FIFA 17, in my opinion, shows the pace and the "scariness" of Liverpool on the break. But I've noticed that when I'm trying to pass the ball forwards, my players will slowly jog on towards the goal (not the ball) while the opposition defender ROCKETS towards the ball and intercepts.
That's just scratching the surface of the issues - you've also got the weird AI-only ball physics where they pass at 200mph (whilst doing tiki-taka), tackling is next-to-impossible on occasion, as is dribbling (because the AI's tackling is fine)... Etc...
As for FIFA 18 - ultra-fast physically-impossible swivels to hit a first-time pass straight to the striker over and over again with no thought towards tactics or "team traits" whatsoever (what a complete lie that was on EA's part).
The thing with 18 is, I feel like if it could be dragged (kicking and screaming) back to having 17's attitude towards moving up the pitch (i.e. not just smashing it forward for 90 minutes), it could be brilliant. But I'm not a FIFA editor, so I don't know how you'd begin to change the AI's decision-making (it's not just "lower these attributes by X" because it's not about player ability, it's about the AI's pass choices).