The principal difference between Major League Soccer and the other major North American pro sports leagues is that MLS competes in a global marketplace for players.

While the NBA, NFL, NHL and MLB can boast an almost exclusive collection of the world’s top performers, there is no monopoly on talent in American soccer. Those gifted athletes who choose MLS are limited, valuable resources—they elevate the level of play, attract fans and lend credibility to a league that’s a century younger than the competition.

Over the past three weeks, MLS has suffered an unprecedented, and violent, talent drain. Last year’s league MVP David Ferreira (FC Dallas), budding star Steve Zakuani (Seattle Sounders), Montenegrin national team fixture Branko Boskovic (D.C. United) and Real Salt Lake playmaker Javier Morales all were lost with long-term injuries resulting from tackles by players sorely bereft of similar pedigree and skill.

Boskovic incurred a torn ACL. The other three suffered grotesque leg fractures that churn the stomach upon viewing.

“With all these things happening, you have to move away from coincidence. Coincidence is if I get hit once by lightning,” Dallas coach Schellas Hyndman told Sporting News.

Yet MLS, despite the obvious problems caused by the loss of four top players, has been reluctant to admit or address the problem. Perhaps expansion has over-diluted the talent and referee pool, or maybe higher stakes are spurring defenders to take more chances. Either way, it appears it's open season on MLS’s top talent.

“It was something that was bound to happen at some point in time. The way he plays, he’s a marked player. If you want to stop FC Dallas, you have to stop David,” Hyndman said.

D.C. coach Ben Olsen said, “It’s a little alarming when it’s the players that people pay to come watch. And that’s what we don’t want as a league. We can’t afford that as a league.”

MLS appears willing to pay the price anyway.

The men who brought down Ferreira and Boskovic escaped sanction, even though both committed challenges from behind. MLS rules stipulate that a tackle not resulting in a red card can merit suspension only if the league’s disciplinary committee (whose identities are kept secret) unanimously agrees that the play was an “egregious or reckless” red card offense.

Brian Mullan (Colorado Rapids) and Marcos Mondaini (Chivas USA), the players who injured Zakuani and Morales, respectively, each was ejected by the referee. Two weeks ago, when Mullan was handed a 10-game vacation for his shocking retaliatory assault on Zakuani, it appeared that MLS had seen the light. Zakuani will be missed. Mullan won’t be.

But then Thursday morning, the league took a troubling step backward in issuing Mondaini only a four-game ban. MLS executive vice president Nelson Rodriguez, who doesn’t sit on the committee, explained the difference between the two tackles.

He called Mondaini’s takedown of Morales “late, clumsy, and from behind. It was also, however, seen as an attempt to prevent his opponent from scoring. (Mullan’s tackle) did not serve such a purpose. Rather, it showed utter disregard for his opponent’s safety and appeared to be driven by anger.”

So, in MLS circles, a cold and calculated decision to snuff out a scoring chance and endanger the player on the ball is far less frightening than a player losing his temper. Surely Morales, and the Real Salt Lake fans who pay to see him play, will have trouble understanding the distinction.

“From a league level, a team level, this isn’t OK. These tackles are ill-advised and they put into jeopardy the safety of other players,” Real Salt Lake general manager (and former MLS goalkeeper, announcer and attorney) Garth Lagerwey said. “Even if you are lunging from behind and preventing a goal, we’d rather have that goal scored.”

It appears MLS doesn’t favor changing behavior through disincentive. Lagerway thinks it’s possible.

“I like to think that we can proactively influence this from our level,” he told Sporting News.

“I am completely OK if you have a mandatory punishment if a player sustains a broken bone or a torn ligament on a challenge,” he said. “When you engage in a challenge like that, you’re putting yourself at the mercy of the league. By choosing to make that tackle, you understand that if something bad happens, you’re going to be punished.”

That sounds like an important, and at this point necessary, step for MLS. It’s time for the team owners who pay for the league’s top talent to protect those investments, and declare that any airborne tackle or challenge from behind that results in a provable injury mandates a suspension—say, five games—that the disciplinary committee can add to if appropriate.

If they don’t, the carnage will continue. Referees are far too inconsistent, and four games forfeited by anonymous journeymen won’t be enough to protect the league’s marked men. Eventually they’ll be extinct.

“They’ve done a fantastic job building MLS so good international players say, ‘Maybe I’d like to live in America,’” Hyndman said. “But look back at the last three weeks and you can see marquee players saying, ‘That’s got to be something to think about. My career could end there.’”