This query type sounds a little funny and can be confusing at first. It's like a BooleanQuery that contains a number of subqueries. Instead of combining scores from each sub-Query, it returns the maximum score from one of the subqueries. The reason for this is that matching may match on multiple fields, and a match on more important fields (should have a higher score) can sometimes have an equivalent score with matching on less important fields due to the number of matching terms. For example, let's say we have a book store application, in which we have a book title and body in our index, and let's say we are searching for The Old Man and the Sea. A match on the title would return a very high score. However, it's possible that there may be another book with the similar title, but with more matching in the body—for example, Young Man and the Sea—that would return a higher combined (between the title and body) score.

In this case, a perfectly matched title may not be returned...