I know what the difference is between subjective and objective. You've actually made my point for me, so I don't get where you're coming from.
Smalling could play 30 2-metre safe passes to players in his own area and win 20 headers in non-threatening duels but lose his man once to concede a goal. One could not argue that his stats were impressive but portraying him as a quality defender based on that data would be purely subjective. You would have to analyse every single piece of his data to be objective as to whether every tackle, every pass, every aerial duel won had any bearing on the game.
You wouldn't call a team's top scorer prolific if he had 30 goals for the season and 25 of them were penalties, would you?
Yes, you would.
And a lot of the stuff you described can be narrowed down with stats. Not to miniscule and minute detail, but enough to know whether someone is actually good at something or not.
For example you wouldn't need to look at every single tackle a midfielder makes to work out whether he's good at tackling. You'd look at how many he makes in comparison to other midfielders, and how often someone tries to run past him with the ball. If players run past him with the ball more often than he tackles them, you don't need to look at every specific piece of footage to work out if hes a good tackler. The numbers themselves tell you that more often than not a player takes him on and goes past him.
The player I'm talking about is Fred. An example of a player who makes more tackles than times beaten by an opponent trying to take the ball past them might be Ander.
Despite this there were specific moments last season where Ander was beaten by a player. Of course a poster would note this and then claim he's not very good. Because he got beat, once. Despite the fact that he won the ball at a better ratio than most players. And thats what really matters, how often players do something, how much you can rely on them to do something over the course of a season. Not whether they look good doing something once or twice in a highlights video, suggesting they're a good tackler but in reality they make 1 tackle every 5 matches.