First of all there is the hero factor. Football's very nature produces heroes from every position and every stage of the game. Every play comes down to a battle between individuals working in the confines of a team. Every snap triggers a battle of wills and strength on the line of scrimmage. Every running play challenges the other team to stop this individual carrying the ball.
Every pass has the potential to be picked off.
In each case, one man can step up, defy the opposition, and win the battle on his own. The lineman can sack the opposing QB for a major defensive stand. A running back can break out a big run and score. A defensive back can read the passing play and make an interception. Often times, these events can be critical to the outcome of the game or even the season.