Toss the oats, sugar, honey, cinnamon and pecans until mixed well. Spread into an even layer on a parchment paper-lined cookie sheet.
Bake in pre-heated 300-degree oven until golden brown. Turn off oven, leaving the tray in for an additional 10-15 minutes. Remove and cool.
Break into crumbles. Arrange the watermelon balls in 6-8 small bowls or wide-stemmed glasses and top with the oat crumble.