Can FC Dallas overcome the loss of Mauro Diaz and make American soccer history?

FC Dallas were the best team in MLS ... and then they got caught in a nasty transfer deal and were forced to let Fabian Castillo go to Turkey. Despite losing their second-best player, they were still the best team in MLS and beat the Seattle Sounders on Sunday to put them on track to win the Supporters' Shield heading into the final week of the regular season.

The problem is they lost Mauro Diaz in the process. Their playmaker, and best player, tore his Achilles in that win over the Sounders. Now Dallas may be set to pick up the Supporters' Shield, but their chances of taking home MLS Cup look dimmer than ever.

If that wasn't tough enough to swallow, there's a good chance that MLS Cup is the only thing that separates FC Dallas from American soccer history.

FC Dallas already won the U.S. Open Cup and they're a win on Sunday away from taking the Supporters' Shield. Then, they would just need to win MLS Cup to be the first team to ever win the domestic treble.

To lose Diaz at all is cruel. To lose him at this point, with history within sight, is just unfair.

With Diaz out, FC Dallas will have to find another way to create chances. They've done it before by swapping out some of the creativity he offered for pace. Instead of repeatedly putting the ball at his feet and letting him shift defenses to create space then exploiting it, they would turn to Castillo on the wing. Teams couldn't keep up with him. Add in Michael Barrios opposite Castillo, and Tesho Akindele with Max Urruti up top, and Oscar Pareja's team could out-run most everyone while still being skillful enough to keep the ball.

They weren't a Route 1 team without Diaz, but one that could play the ball well enough, then beat you with their pace. Whether that was with the pace of their press, their pace on the counterattack or their pace in small spaces that turn innocent passes into scoring chances, they were too fast for most teams. But so much of that was made possible because of Castillo. He was their gamebreaker, for whom defenses had to shift markers over, and who opened up space for everyone else on the pitch.

Losing Castillo was supposed to be a killer for FC Dallas. One that took them from the class of MLS to merely a good team. But it wasn't and they remained the best team in the league because they were so good everywhere else. They were deep, smart and knew exactly what they were doing. They had a system and that system wasn't made by one player. But also because they still had one truly magnificent player who could dictate a match in Diaz. Now he's gone.

There are few MLS teams that can handle losing one of their best players. Rosters aren't deep enough and team generally only have a couple truly spectacular players. But FC Dallas was the exception. They proved that.

Can FC Dallas be so exceptional that they can withstand the losses of their two best players? That's hard to believe.

Pareja will try to beat teams with pace. It's not like Urruti, Akindele and Barrios are suddenly slow. And they have Mauro Rosales, who can give them a real set piece threat, as well as some creativity. Kellyn Acosta, Carlos Gruezo and Victor Ulloa are excellent players as well so they have two-way midfielders who can lock down the center of the pitch. But they don't have a game-changer anymore. In a span of three months they went from two of the best to none.

The treble was in FC Dallas' sights. And it still is. After all, it would be foolish to dismiss them after how well they handled Castillo's departure. But it must feel like it got a whole lot farther away when Diaz went down and grabbed his Achilles.

MORE FROM FOX SOCCER