You’re thinking about the question in a very black and white manner. The question isn’t necessarily referring to the whole game, but how they executed throughout the game.
Lets say you have a game that goes back and forth and it is tied at going into the final minute. Both teams have been playing well and are equally matched. At that point one team turns the ball over every possession and the other manage to score once. They win by 2 points.Now lets think about the same situation, except both teams play excellently, and the other team hits a last second buzzer beater, again winning by 2.
In example 1, the first team lost the game by failing to execute. in example 2 the first team were beaten by a team who executed better than them.
Lets take Jr Smith’s famous mistake during the finals this year. Golden state didn’t outplay the Cavs, on that possession. They didn’t trick JR, nor did they plan for JR to forget the score.
JR smith fucked up and lost them the game.