By far the best way to evaluate football players is by watching them live. When you go to or watch on tv a Barcelona game and watch Lionel Messi you’ll notice that he has a free role. He’ll walk around the pitch saving energy, sometimes jogging into space. When he gets the ball, he’ll often pass it without dribbling.
But sometimes he’ll get the ball and suddenly accelerate, using his insane ball control to beat a couple of defenders and cause panic in the defence. He also has wonderful creative vision, and his passing and finishing ability is elite, he’ll make passes and score goals that are unbelievable.
Because the defence know this, they’ll often assign at least one guy to man mark him, and always be quick to close Messi down. This of course creates space for other Barca players.
In this way, you could look at stats for a game showing that Messi didn’t run much, didn’t score or make an assist. You could then look at stats like pass completion percentage and shots on target. But you’d need to watch the game to see his true impact. Did he create space by tying up defenders? Did his passing create anything? Were shots close to going in or easy saves? So many variables.
Obviously Messi is an outlier - he scores 60 goals a season, you don’t need to watch him play to realise he’s a great player. But the same theory applies to lesser players. And as I said in my previous post, there often isn’t a definitive “player X does this so therefore they are good” when assessing players who aren’t primarily goal scorers.