By Mike Steinberger

Just before daybreak last Monday, a speedboat ran aground in the Florida Keys about 100 miles south of Miami, having outrun and outfoxed the US Coast Guard during a harrowing six-hour journey from Havana. Aboard the boat were nearly 20 Cuban asylum seekers, among them the wife and two daughters of New York Yankees pitcher Jose Contreras, who defected to the US two years ago.

Contreras is one of more than 50 Cuban ballplayers who have taken the one-way trip across the Florida Straits in the last dozen or so years, an exodus that has robbed Cuba of some of its biggest sports stars. However, Fidel Castro's loss has not yet proved to be Major League Baseball's gain. Broadly speaking, the Cuban contingent has been a complete bust. The reunion of the Contreras family is an uplifting footnote to a story that has not yielded many happy endings.

Contreras, who defected while on a visit to Mexico with the Cuban national team, is easily the most expensive disappointment. Following a fierce bidding war with the Boston Red Sox, the Yankees signed Contreras on a $32m (£19m) four-year contract. Although he has had moments of incandescence, he has generally been an abysmal addition to the Yankee rotation, and there has been speculation in recent weeks that his career in pinstripes may be nearing its end.

The 32-year-old Contreras had his best start as a Yankee on Sunday, dominating the New York Mets as his wife and daughters looked on. But at this point, it is going to take more than one good outing to change perceptions.

The Yankees got substantially more mileage out of Orlando "El Duque" Hernandez, another Cuban emigre who contributed several World Series masterpieces to New York's three consecutive championships between 1998 and 2000. His brother, Livan Hernandez, was equally lethal in leading the Florida Marlins to a World Series title in 1997. But the Hernandez brothers have been the lustrous exceptions.

By and large, Cuban players have fallen far short of expectations. No doubt, culture shock and homesickness have played their part. However, a bigger problem is that quite a few of the defectors have been past their primes.

Joe Kehoskie, a sports agent who specialises in Latin American prospects, says that a number of Cuban players left either because they ran foul of the authorities or because their skills were in decline and they wanted a financial windfall before retiring. According to Kehoskie, it is not uncommon for defectors to fib about their ages.

Major League clubs, he says, have grown disillusioned and are no longer showing much interest in Cuban talent: "Back in 1998, I had a workout for five Cuban players, and 24 teams sent scouts. Now, maybe six teams show up. Teams have become extremely wary. They are sceptical of the abilities, the ages, the backgrounds." Kehoskie says he has soured on Cuban defectors for another reason: many of them now use smugglers to get to the US and the exodus has taken a somewhat shadowy turn. "It has become a smuggler's business," he says.