When someone lands an acting gig, and his day job is anything besides "actor," he's graded on a generous curve. This holds true for summer blockbusters and local commercials alike.
Despite the low expectations, non-actors often give a performance on-screen so stilted—so terrible—that no curve can salvage it. Few celebrities are more guilty of these acting atrocities than athletes, and no situation is more ripe for failure than one where an athlete is supposed to be funny.
Since some commercials featuring athletes trying to both (gulp) act and be funny are so freakin' bad that they transcend failure and give us the commercial equivalent of The Room, usually your first instinct is to cringe.
However, such a large margin for error presents a great opportunity for a solid performance to far exceed expectations—to transform a good job into a great one.
When an athlete nails it (on a curve or especially on his own merit) everything comes together, and a hilarious, effective commercial is born. This may be a rare phenomenon, but that just makes it even more precious.
These are athletes who actually made legit, funny commercials.