Generally speaking, when a team's winning, it'd be running more to keep the clock running later in the game. Also a "good team" is usually said to have a good run defense, and that's also partly because when you're leading late in the game, the other team's passing on you, so of course you'll yield fewer yards on the ground. You do that for a few weeks then TV analysts will come to the conclusion that a team has a good run defense. A good running game is certainly a piece of the puzzle, but often times it's the effect of winning, not the cause.