i think it mainly causes a problem with balls over the top, because the defenders have trouble knowing where to go, in low res they only have to be within a few feet of another player and their avatars are touching meaning the game accepts that they are able to tackle each other etc, but in high res that same position converts to being yards away and in no position to win the ball.
I've never tried playing long ball but i guess you could end up with a 6-6 draw or something if you did.. the opposition strikers were equally as rubbish as mine though, clean through means a miss about 85% of the time. (Only in matches vs me though. calculated results usually give the strikers all the goals
)
It also seems as if players stamina reduces a lot faster, i was often finding my wingers falling into the 60% zone during the 2nd half, which i never saw before this season.
It's not all doom and gloom i suppose, it makes the game harder for those who find it too easy, and it certainly looks and feels about 10 times more realistic than when it's in low res. There is a definite feeling of pace for the fast players and shot power for the strikers/midfielders which you just don't seem to get in low res.
i still managed to be top of the league despite all those problems, but it was just ruining my enjoyment watching my 30m striker get about two sniffs of the ball in an entire match which he didnt do anything with, and definitely killed my enjoyment watching my "man marker" standing 50 yards away from the man he's meant to be marking as he gets clean through on goal for the 10th time of the half, so i'm definitely glad to be back in 1024x768 (or 1031 by 775 as my screenshots tell me - don't ask me .
)