Before the game, Bulls coach Tom Thibodeau predicted a "cage match."

Physicality, in other words, would be Chicago's solution to Miami's big, strong and super-quick LeBron James and Dwyane Wade, who tend to make layup after layup. Good, solid defense doesn't cut it against those two. The recipe? When they get a step on their defenders, when layups and dunks look likely ... tackle them, hit them, bring them down out of the sky.

It started a few minutes into the game, when an eager Kirk Hinrich, despite having perfect defensive position, crashed into an open-court James rather than attempt to strip the ball, draw the charge or contest at the rim. Minutes later, Hinrich was directly in James' path, in position to draw a charge or try to poke the ball away. His move? A bear hug that ended with his own head whacking the floor hard.

Moments later, James was zeroing in on a reverse layup or dunk, and the Bulls' Taj Gibson -- in no position to touch the ball -- swung hard and connected with his hand directly to James' head. Instead of dunking, James ended up on the floor, checking his teeth. And that was just the first quarter.

Why, again, is this fun to watch?

Although the Heat have sent the league video of hard fouls on James and Wade, with particular emphasis on hits to the head, players like James seldom admit such things affect them -- even as a growing body of data suggests the best players put off driving when they don't feel they have to.

Two weeks ago James denied hard fouls affected his thinking, saying after a win in Philadelphia: "I'm a football player. I'm good. I can't worry about what may happen. I live in the moment. I'm an attack guy. I'm an attack player. I don't really make my mark on the perimeter."

But after the loss to the Bulls, James was more frank, telling ESPN.com's Michael Wallace: "A lot of my fouls are not basketball plays. First of all, Kirk Hinrich in the first quarter basically grabbed me with two hands and brought me to the ground. The last one, Taj Gibson was able to collar me around my shoulder and bring me to the ground. Those are not defensive ... those are not basketball plays."

In an era when the NBA is watching closely to reduce concussions and head injuries, James was obviously hit hard in the head by Gibson twice, and also endured an open-court collaring that was initially ruled a flagrant. James' head also was struck once by a driving Nate Robinson, and for good measure, again as a parting gift from a Bulls fan as James made his way, after the loss, to the locker room. Wade also was sent sprawling to the floor spectacularly and regularly.

On ESPN, Bill Simmons called Wednesday night's Bulls win over the Heat the most important regular-season game since the 1990s. The winning strategy was from the 1990s, too. It's called Tackle Basketball.

It's not an accident. It's a strategy that works because of a loophole in the NBA's rules.

Stu Jackson is the NBA vice president of basketball operations, the man responsible for keeping those rules dialed in correctly. He's frank that he hates how the famously rough Knicks played back in the day, and touts rule changes as having made the game much more pleasing, and about artistry. Jackson says "that what keeps us up at night" in his department is the fear that the game would return to the artless way it was played in the 1990s.

I wonder how Jackson and crew slept Wednesday night.

This is not about babying James or anybody else. This is about the league encouraging the best possible version of the game, the one that works best for players and fans. Would you rather see James dunk or get hit in the head? Would you rather see Hinrich meet James in the air or in a bear hug?

This is ultimately about answering this question: What is basketball, and is tackling part of it?

The walls of my office are covered in hoops books. Some are of the “how to play” variety. I just took a stack of them -- by everyone from Walt Frazier to John Wooden -- over to a comfortable seat and spent an hour reading up on how the experts say good defense ought to be played.

They talk about footwork and brains. They talk about keeping your torso between your man and the basket, staying on the balls of your feet, knees bent, hands up and mind alert. They talk about staying on the ground for fakes and talking to teammates. They also talk about many layers of thought: tracking both the ball and your man, memorizing the tendencies of every player on the court, knowing who likes to go left, who telegraphs passes, who never passes, whom you should never leave open.

It’s the art and science of basketball, in a shape-shifting formula of movement, work ethic, preparation, smarts, muscle and know-how, all working toward the common goal: making sure you don’t get beat.

But in the NBA in 2013, even if you do get beat ... defenses have one move left, and it’s not described in books.

The move goes like this: That guy with the ball? Clobber him. The harder the better.

It happens in every game, every night.

We tell ourselves fouls are mistakes, a surplus of effort or grit from players going a bit too hard trying to play the kind of defense described in those books. And some fouls are like that.

Other times it’s a lot less nuanced. Other times it has nothing to do with basketball. Instead, it’s the opposite of sportsmanship.

Many of the players doing this are among the nicest in sports. They are neither imbalanced, deranged nor in need of help.

So why would generally even-keeled men endanger their colleagues by making what should be the game’s prettiest plays -- flashy finishes at the rim -- into the ugly kind of basketball that is proven to turn off casual fans?

They’re doing it because it works. The fact of the matter is that, because of a flaw in the NBA rulebook that’s only truly becoming clear, it’s almost always better for NBA teams to foul really hard than give up a layup or dunk. The cost of the hard foul is a pittance compared to the benefits. They don't just stop fantastic baskets, they also make potent scorers think twice about driving at all. Everyone on the court knows a couple of free throws is a bargain for all that.

That’s why these days very hard foulers are getting high-fives from teammates and pats on the backs from coaches; they are helping their team win on a technicality.

And it’s going to keep happening until the league does something about it.