In real life, the combination of mostly zonal marking with some man-on-man marking is likely to be superior to zonal marking only, and both are superior to man-on-man marking only.
In this game, either zonal marking or man-on-man can be used, but not both at the same time. So, logically, zonal marking should be superior, but some users have said that man-on-man marking gives a defensive boost.
It is said that the use of the man-on-man marking is more condition consuming to the team using it as compared to zonal marking. In that case, I think that the opposing team should also lose more condition because its players will have to run around more to get unmarked.
Some users have said that:
(1) zonal marking is best for playing against stronger opponents;
(2) man-on-marking is best for playing against weaker opponents.
This does not make any sense, if both points are considered. If (1) is correct, then (2) is not correct. If zonal marking is best for facing stronger opponents, then why should it not be even better for facing weaker opponents?
Please post on how you think man-on-man work in this game, and provide feedback on what advantages or disadvantage it gave your team(s).