Yeah
Coaches know MUCH more than any of us do, that is obvious. But at the same time they make hundreds of little decisions in every single aspect of the game every day. They make plenty of decisions that can often turn out to be 'wrong'
football isn't an exact science, some armchair fan who knows enough about football but nowhere near as much as a manager can point out flaw in the managers decisions, even before it becomes a matter of hindsight. That's just how it is
Would they/we do 1/5th as good of a job in the same circumstances as a top manager? $#@! no.
Can they/we point out where managers have gone wrong, can we disagree with certain decisions and be proven correct? Yep, of course we can.
Basically, you don't have to be as talented/experienced/good as somebody in every way possible to disagree with any of their decisions.
Having said that, i'm happy enough with how much playing time Coman is getting. He's very talented by the looks of things, but he's not some 1 in a million beast. We should not be relying on such a young raw player to do anything important at this point.
In his early 20's, game time is key. But at this stage, he'll be benefiting massively from training in an elite environment under a successful coach with World Cup winners, league winners and top end International class players.