When watching or playing sports, we enter into a sort of contract that includes accepting that the outcome -- while primarily influenced by what athletes do on the field of play -- is also bound by a set of rules that can be highly subjective.

These rules are enforced by referees and officials who are trained and do the best they can. But at the end of the day they are also human, make mistakes and have the sum of their experiences as their guides toward making subjective decisions.

Strike or ball? Well, most umpires have seen many thousands of pitches before they call one specific pitch, and they have an idea of what they consider a strike even if it might not perfectly match the textbook definition of a strike.

In basketball, was that a charging foul on the offensive player or a blocking foul on the defensive player? Again, so very highly subjective.

That said, the most infuriatingly subjective call in all of sports is easy to choose. It is pass interference in football, and it is not even close. There might as well not even be a rule governing what is and what isn't pass interference these days because, if you watch a game, you often will be clueless when a flag does or doesn't come out.

If you watched the Gophers vs. Michigan game on Saturday, you saw coach Jerry Kill express that frustration. He was so hot after a pass interference call in the end zone, he could have melted the stripes right off the ref. The Wolverines might have felt the same way later in the game with a call that went against them.

College players, too, have learned from their pro role models how to not only sell the pass interference (careen off balance and flail if all else fails) but to demand it. It's not uncommon to see a wide receiver making the "pulling the flag out of the hip pocket" motion while gesticulating at a ref -- sometimes while the ball is still in the air!

At least in college, of course, the penalty on a deep ball will only cost a team 15 yards. The NFL would do well to adopt that rule; anyone who watched Troy Williamson knows that even the most flagrant of defensive pass interference violations does not prevent a sure-thing catch of a bomb. Simply awarding a team all the yardage that would have come from a catch? Too much.

If a rule is subjective by nature, however, there is no perfect way to craft it. We think the defensive players should get more leeway to bump, nudge and even occasionally grab. Or maybe an offensive player who flops and tries to sell pass interference could be nailed with unsportsmanlike conduct?

Or everyone could just try not to get so frustrated when the call doesn't go their way? If you are able to do that, you are better than most of us.