The other thing is that player evaluation is an extremely imprecise science. For example, even with all the information modern professional sports scouts get ab

The other thing is that player evaluation is an extremely imprecise science. For example, even with all the information modern professional sports scouts get about their prospects, many new players still wash out and are busts. The science just isn't precise enough to give definitive answers (and it's possible that science can't give answers in some of these cases). So there are a large number of judgement calls to be made, even with all the information available. A fan might be correct when they say, "Coach should have played X instead of Y.", but the trick is knowing that in advance. And knowing hundreds of other things in advance too. Maybe coach got that one decision wrong, but hundreds of others right. The fan is unlikely to get that many correct on a percentage basis.