I'm not sure where to post this exactly, since this is a general advice for pretty much every FOX Engine PES, so I think this is probably the best thread for it.
I think many would agree that in the higher difficulty settings the CPU plays in a much more cheap way, usually doing the same efficient plays perfectly over and over, regardless of the team you're up against, so every match feels very similar and frustrating, more end to end and robotic at times, so the best way to preserve team individuality and realism, to keep things as organic as possible, is sticking with the lower difficulty settings, like Regular and Professional.
One of the main issues with this is obvious, it can become too easy to win with time, so one of the solutions is to play in FUMA, to make up for that less challenging difficulty, that way you'll make more mistakes, missing goals and lose the ball more often. However with time a new problem might show up, you start getting used to FUMA, and the only solution seems to be going up to the higher settings that to many are not ideal.
I think I've found a solution, a surprisingly simple one too, all you have to do is change your camera.
This works especially well in the FOX Engine PES games, because they have customizable cameras, I admit it's not as customizable as I'd like, but those sliders in the Wide, Dynamic Wide and Stadium cameras are very useful. If you like playing in a low zoom, high height and low angle camera, like I usually do, then it doesn't take long to get the hang of FUMA, because it's very simple, you point in that direction and the ball goes there, however when we start adding in things like a lower height or a higher angle, it becomes a lot more difficult to pass and cross, but especially to shoot, so you'll go back to making more mistakes and missing more chances, even if you're used already to FUMA.
You have to relearn where to aim to get a certain result, and that takes time, it's almost like relearning FUMA all over again, with the main difference being that you already have an understanding on how it works, and practice. This works in general, any camera switch is going to have this effect, all that changes is how intense that effect is, depending on what camera you were playing on, and which one you switched to.
I know this might not be the perfect solution, but it's what I came up with, and it's working well enough on my end, I was playing with the standard Wide camera, with Zoom: 0, Height: 5 and Angle: 0, now I switched to Zoom: 2, Height: 2 and Angle: 0, a slider setting that PES2018 calls Pitchside, it reminds me of the camera with the same name on PES2012, which I loved playing in, I'm missing a lot more of my shots now and making more mistakes in passing too, so Professional it's challenging again, thankfully, no Top Player for me.