What this means. Take every three-year stretch since the fund had a NAV, one starting each month, and ask two things of each: did it beat the typical fund in its category, and by how much. Counting the wins tells you the record does not depend on when you happen to look; averaging the margin tells you whether winning often was worth anything, because four small wins do not pay for one large loss.
How it is measured, and the case against
A fund that beats its category in most rolling three-year windows has a record; one that beats it in a few has an end date. How often it won and by how much are different questions, and this card answers both, because a fund can win four windows in five and still be behind across all five.
How often has it beaten its category, across every window?