Loads of posts have mentioned this so I'll only quote the one... this is something that's long fascinated me.
Marshall played his first genuine Test (had had a few irrelevant games during the Packer Schism) in 1980 in England. But even now, he wasn't a first-choice. Between the end of the Schism and the series in Australia in 1981/82 the first-choice was Roberts-Holding-Garner-Croft. Marshall, however, played 5 games (out of 10) against England in 1980 and 1981 when various bowlers were injured, and also the full series in Pakistan in 1980/81 when Roberts and Holding both withdrew.
It wasn't until Croft was dropped in 1983 for the home series against India that Marshall became a first-choice. However, by this time Roberts was about to retire. So for just 2 series (this in 1983 and the next against the same opposition away in 1983/84) Roberts-Holding-Garner-Marshall could be said to be the attack of choice. And unfortunately, Roberts missed 4 of these 11 games, and Garner 7 of them. Their places were taken by Wayne Daniel (like Croft potentially as good as the big four, but who ended-up with a very short career) and Winston Davis (who was several classes below).
So the reality is that Roberts-Holding-Garner-Marshall was virtually a fantasy. Never were they a constant presence in the West Indies attack.
In fact, there was never any real consistency in West Indies' fast-bowling between 1976 and 1986. Except for one thing: almost everyone they picked (bar the odd Winston Davis and Milton Small game) was damn good. It was depth, not injury-free-ness, that made them so good.