Sometimes the biggest difference between a joke being funny and a joke falling flat is the contrast used. The contrast can be in the timing (leaving a pause before the punchline/action), action (one movement among stillness), delivery (quiet lead-in to explosive delivery), character (see funny pairs: Laurel and Hardy, Felix and Oscar, Lucy and Ricky, Buzz and Woody, etc), or pretty much anything else in the composition and acting.
Watch the video below for a few extreme examples:
First of all, why is this funny?
Contrast in Setting
Why it works: The overall humor in the theme is seeing athletic giants performing their required actions (which require speed, precision, strength, and focus) in a state that is completely contrary to their norm (slow, tired, weak, and confused). Not only do they perform terribly, but the rest of the world is seemingly oblivious and carries on as if nothing is different.
How it could have failed: If played realistically, this game would have been stopped within 5 seconds of someone collapsing to the ground in a drug induced stupor. As funny as it is to see players lumber around like idiots, it is the obliviousness of the rest of the world that pushes the humor. The contrast between our own reality and this fantasy game keeps us interested.
Contrast in Action
Why it works: One of the constants in this entire piece is the sleeping player on the field that contrasts the main subject. In every shot the sleeper appears the screen is full of movement (some of it small) yet he remains in the same position each time. He is the constant that keeps us "grounded" in the video as everything else around him changes. He may even get the biggest laugh by being featured as the only person on screen after the big hit at the end. His sleep contrasts our own reactions by being oblivious to the world we are laughing at. As the entire world collapses in chaos and pain around him he remains unaware and peaceful.
How it could have failed: Not having him present would have changed the video into a collection of somewhat random mini scenes of crazy football players. Having him him move or react to the world around him (other than a small jump in his sleep) would have broken the contrast to the world around him and the viewer.
Contrast in Character/Emotion
Why it works: When two or more characters share a scene and one character is "straight" while the other is "looney" you have humor: the goofy player interacting with the unfazed ref, the comparison shots of the offensive and defensive lines (serious white players, amused red players), the wiggling man and the stationary laugher (whose utter collapse the contrasts the stationary wiggling), and the happy, peaceful ball carrier vs. the serious and violent tackler.
How it could have failed: Having both teams acting goofy would be amusing but not as much as with contrast. Some of the least funny scenes (in my opinion) are the shots of single players doing different actions. Maybe one or two work, but by the time we see the 4th red player twitch and fall asleep standing up we are tired of the gag. If a few of those scenes had a white player angrily staring at red player as he giggled/twitched/yawned/bit-his-tongue the scenes would be much stronger They could also cut a scene of a single white player being serious prior to cutting to the corresponding goofy player across from him.
Contrast in Timing
Why it works: A player laughs at the strange, fluid movements of his neighbor then suddenly collapses in the same manner. Yes, there is contrast in character between the shaking man and the pre-collapse man. Yes, there is contrast in action with their two stances. But the genius of this shot is the timing of the collapse. The player remains upright long enough for the viewer to survey the scene, laugh at the humor in the wiggling man's actions, and right when the interest in him wanes the "grounding object" of the shot collapses. Without the viewer realizing it, the seemingly normal player builds anticipation for the unexpected (he is the only character not acting abnormally) and once the humor wanes from the other element of the shot he rewards the anticipation by suddenly collapsing into a heap.
How it could have failed: By immediately collapsing without giving the viewer a chance to interpret the scene. Or by waiting too long and collapsing after the viewer grew tired of the scene. A similar gag did fail too, as the Mascot also collapses in a similar fashion but it happens immediately when the shot appears. An earlier shot established the Mascot as being stationary but since he was not the main focus of the shot most viewers never noticed him. If the shot gave the viewers enough time to see all the elements in the scene before Mascot fell then the scene would be successful (although the spooning players add humor through contrast in reality) .
Contrast in Composition
Why it works: My favorite shot, all the players are stationary (but fidgeting, except the sleeping man) and one player begin running in the wrong direction. What makes the shot work excel is not the contrast in action, but the contrast in the composition of the shot: We see the widest shot of the entire piece and the camera is stationary (just after tilting and shaking in the previous shots) when suddenly a very small portion of the screen has a major movement.
How it could have failed: Yes, the contrast in action is funny, but if the camera was a close up shot and panned as the guy ran it wouldn't work. The humor is in the placement of the characters and lack of movement in the shot which is suddenly broken in a small portion of the screen.
These are just a few examples of how contrast in this commercial makes it as funny as it is, see if you can pick out more...