Aside from the agents, some other factors to consider:
Age:
The age at which players attain their highest value and marketability has drastically reduced in the last 10 years. Whereas 10 years ago, a player at his prime (age 26-29) would command the highest wage, the transfer market now focuses not only on talent but potential. So a player age 18-22 would fetch the highest value knowing that he can produce the goods at a younger age, and also be a profitable investment should the club desire to sell him on. Most of our best players fall outside the age of highest marketability and thus will not attract the attention of the better clubs. Even the best players in the world are not commanding the sort of interest they would have now because of their age eg. Crespo is 29, available on the cheap, but interest so far is not forthcoming.
Transfer Market:
The transfer market is tight right now with a focus on the best bargain for the least money. Gone are the days of inflated player fees like when Zidane was sold, where clubs would spend astronomical amounts on players. Now, apart from Chelsea and Real Madrid, it is rare to find a club spending over £20 million for a player. Clubs have become much more prudent with their investments and as such, for a club to take a chance on any of our Trinidad players, they would have to be guaranteed that their performance will bring instantaneous rewards. The TT player would have to be a cut above the rest and I dont think we have many players right now that we can guarantee will light up the higher leagues.
Global Availability of Talent:
Football has become such a global game now that quality players can be found in any corner of the planet. The last 2 World Cup has shown that the gulf in the class of national teams across continents has shrunk enormously. So whereas 10 years ago, if you were a manager, you know you could only get a good player from europe, south america, a few from Africa, minority from elsewhere, now you can pretty much get that anywhwere. This has increase the competition for the places available at clubs, and only the best talent is going to the best leagues. Consequently, whilst years ago, the world cup would be a venue to unearth hidden talent and a player could get a contract off performances, nowadays, everyone pretty much knows about all the players even before they get to the tournament. And even if our players did well there, its not a guarantee they can maintain that over the course of a season.
Style of play:
The World cup exhibited that the global game is changing such that success does not go to the team with the most talented players (Argentina, Brazil, Ghana) but rather the teams with the best tactical approaches (Italy, France, Germany). As such, not so much emphasis goes to a player who is blessed with talent to burn, than a player who is physically fit, disciplined and can best adhere to a tactical system. I suspect this is part of the reason why there's not as much confidence in our players as anticipated because there may not be the guarantees that our players can keep up the high standard of performances through the duration of a season.
Just some thoughts for consideration..