Manual goalkeeping is a risky endeavour, but actually can work and is a very useful mechanic. I have to caveat that by saying that it isn't perfect; it could do with movement when you have the keeper under your control being looked at. Stick movements should be more like keeper face-up movements, with a press of the stick to the keepers left or right being a lateral movement.
I saved what would have been a certain goal in an online match a few nights ago using it. It is just another one of those amazing wee things you can experience in the game when you get it right.
As for pass support, I think the best matches I have played on PES2017, offline or online, are when I use PA1 but find myself using manual modifier passes for the more ambitious or simply tempo varying stuff. I played against a fellow, like-minded Scot, the other night there on myClub and after the match we exchanged messages complimenting each others use of the PA1/Manual Modifier combo. An excellent wee "moment" from all my years playing these games. I even apologised for my team maybe being a wee bit OP compared to his (though it was technically my 4 star team I used)
It's stuff like that has me not only optimistic about PES2018, but thankful the developers have kept Manual Modifier as a thing, and only hope more people will utilise it, along with the off-the-ball controls, which I find go unused by many in my online experience. The Dynamic 1-2, combined with Manual Modifier passing, can allow you to create some beautiful play, and you can even combine that with another runner if you quickly use Teammate Controls immediately after the Dynamic 1-2. Yes, it can be incredibly risky and leave space, but it is a wonderful thing engineering all that movement and pattern to play with your fingertips.
And then you can consider Attack/Defence level and Fluid Formations on top of all that above. The game has so many tools at the players disposal and it is that which has given recent offerings, especially PES2017, more legs. I am very confident that PES2018 will do similar for me. I hardly notice AI "cheating" or scripting these days as I am too busy experimenting with all the possibilities and if I get spanked off the AI or a human opponent (preferrably a like-minded one) then so be it. I play very much to create first and compete second these days and I love that the game can offer that, after it is the other way about in the first few months.
Postioning off? Foul count not realistic? AI scripting? I don't notice any longer as I am totally focused on what I can do when I get the ball and try to make full use of everything at my fingertips. That is the real challenge for me now and I love that PES can do that. I think PES2018 could allow for even greater expression, so pardon my optimism.