Andrew Luck is a smart dude.

He graduated from Stanford, after all.

The now-former Indianapolis Colts quarterback is smart enough to know he no longer wants his body to be beaten to a pulp.

He's smart enough to know he no longer wants to be in pain.

He's smart enough to know that the money and the fame may not be worth it. Not when a 300-pound defensive lineman lands on you, or when a 230-pound linebacker who runs a 4.4-second 40 smashes into you with the force of an auto accident several times a game for 17 weeks (or more).

He's smart enough to know there's more to life than football.

And that should scare the whistles out of the NFL.

When one of the biggest stars at a premiere position in all of sports decides the risk is no longer worth the reward, that should raise every eyebrow in the league office.

When a quarterback who should be in his prime at age 29 announces his body has been ravaged so badly by the game he is in physical and mental pain and needs to hobble away, that should send every owner into deep concern.

We've known for a long time how violent football can be, especially in the NFL.

It's not a contact sport; it's a collision sport.

And the collisions are getting more extreme as players get bigger and stronger and faster.

Luck's list of injuries is staggering.

Concussions. Lacerated kidney. Torn labrum in his throwing shoulder that cost him a season. Busted ribs. Now a perplexing leg/ankle/foot ailment that has shown no signs of abating.

Luck basically waved the white flag. He decided his quality of life was more important than the $58 million he was still owed on his current contract with the Colts.

He's already made enough money and he wants to enjoy it.

Hard to do that with chronic, debilitating pain.

Luck wanted to do it the right way. He was going to meet with his teammates and then hold a press conference to announce the news. But it broke during the fourth quarter of the Colts' preseason game against the Bears and spread quickly in the stands in this age of Twitter.

When Luck walked off the field at the end of the game, the fans booed him.

It was a raw, knee-jerk reaction and one I don't think is indicative of the fan base in Indianapolis.

Some of the other criticism of Luck's decision was more calculated.

Many questioned why he retired so close to the start of the season. People forget, however, that he had not yet been cleared to play and there was no time table on when he would see the field again. He still has stubborn pain in his leg.

Also, you can't put a time frame on mental pain when it's convenient for someone else — like fans and owners, both real and fantasy.

The worst stakes came from those who called Luck soft.

Take a look again at the injuries he played through and endured and ask if he's soft again. People miss a week of work with a sore throat.

Some also questioned his loyalty.

Luck owes the Colts nothing. People also forget that the organization would release any player, even Luck, the second they deemed he could no longer help them win.

Owners don't make decisions based on loyalty. Why should the players?

More players are deciding to leave the game early.

That's certainly not something the NFL wants to see.

Luck may be speeding up that trend as he becomes an example to other players.

Mike Kilroy is a staff writer for the Butler Eagle.