So many factors lead to the downfall of West Indies cricket, the most primary reason is their cricket board & their careless attitude towards those players who made their country.
If we really look WI is a nation who has produced all round players. there are few nations who have produced good Batsman or good bowlers but WI have constantly produced batsman & bowlers simultaneously.
For good period of a decade they were mighty & almost at a stage where they dominated every opposition & if I am not wrong they were feared at-least their bowlers were feared by everyone.
WICB earlier, even today never valued their star players in terms of wealth, they always if I am not wrong underpaid their players. They never motivated their players. Imagine if Gayle was an Indian player, he would have been the most richest cricketer but unfortunately every great WI player had a fall out with their cricket boards. Somehow WICB did not pour enough wealth in their cricketing unit & expected players to be patriotic but failed to understand that it is a profession.
Every other country by then have commercialized cricket & with advancement of economics, cricket boards from other nation started to motivate players with money. This policy is still not adopted by WICB.
If you see the way Chanderpaul was treated, in any way I do not see such a treatment for this wonderful talent.