I'm finding arrangements of rectangles and squares, such as in the Simplish pattern linked here to be a good way to combine collections of fabrics when they themselves don't really go together very well.
https://www.youtube.com/watch?v=pie5cWlD8Ps
In the case of sports fabrics, I'd think of a nice green/grass background.
Here are two I've done, "Here Kitty Kitty" and "horse blanket"