John Jarrold has told me a few things from submissions: the entry level for a new novelist is no longer "good", it's now "special". He also told me that agents and publishers, though they might love a good, will hold it back from publication until the market is right for it.
Book selling's a tough game... and, yes, sometimes a book just hits the right spot at the right time. Look at the sheer number of vampire novels that have been unleashed upon bookstores in the last few years. Without a doubt, this is down to the Twilight effect. I sure that had Stephanie Meyer's books not seen the light of day (no pun intended), many others would have either.
Incidentally, my second book, THE THIRD SIDE, is now out on Amazon Kindle and is currently at #4 in Space Opera...