Run differential is the primary indicator of performance (in addition to adjustments for opponent strength, etc.).
As such, teams like the White Sox, who win a lot of one-run games, are luckier than teams like the Indians, who win decisively, and lose one-run games.
Basically, it goes like this: It's not quantifiable that players perform differently in "clutch" situations or in different games, aside from by strict probability -- which is to say, if a player hits .333, he'll have some 0/5 games and some 3/4 games. But he's still a .333 hitter.
In run totals, a team with a lot of one-run wins is one run better than their opponents every game. Is a team who wins every game by one run better than a team who wins half their games by five runs but loses the other half by one run?
Your wisemen don't know how it feels to be thick as a brick...