Comments

There is certainly more than musical talent involved.  There are credentials involved, things like who you studied under, how much your mentor championed your cause, how influential your mentor is, your stage presence and image, which of the international competitions you've won, etc.  The winners of the competitions are those who appealed to the judges most, not necessarily the best musicians.  I'm sure that luck is an element, too.

Well, remember that even the good ol' J. S. Bach was forgotten for quite a while, until Mendelssohn (I believe) came along and revived that music, performing one of Bach's oratorios. Also, bach in the day (:-P) nobody performed music by dead composers. I believe the reason for this is because composers worked for the church or noble patrons and they composed music as needs for it arose, so they were playing new music all the time. With your particular composer, after he died his music probably ceased to be heard and a widespread revival may have never happened.

There's also other reasons why some composers stand the test of time better than others. There's a lot of composers from the classical era whose music sounds much like Haydn or Mozart, however any music theorist can list you a number of reasons why Haydn and Mozart are considered vastly superior to their peers.

Actually I don't think luck has too much to do with it. 

While there's been plenty of time to consider who were the better composers from the baroque, classical etc. periods (the historical filter), the number writing music has grown exponentially since then. There's tens of thousands of people writing music today, so I don't really think it's possible any longer in terms of absolute quality for one or two to be identified out of all the rest as being the greatest, given the diversification of styles. Certain contemporary figures have risen to prominent positions but there's no doubt that others also merit the attention in the same way, aside from the fact that we don't have the historical distance.