This is an excellent question. In MSTW Schedules & Scoreboards there is a games_to_show shortcode argument that defaults to 3 (as I recall). In MSTW League Manager, the slider expands to fill the width of its parent element, and games_to_show is unimportant (which IMO is how it should work to give you the most control.) I need to go back and fix S&S to work that way. (There are also some height issues that can be controlled with CSS, but need some fixin’.) So in the meantime …
Inspecting your page, the div class=box element is too small. I’m not quite sure why. So there are two potential fixes:
(a) set games_to_show=3 (or whatever you want)
(b) add a CSS rule in your S&S stylesheet
div.box {
width : 100%;
}
I know (b) works because a tried it on your page.
Hope this helps.
-Mark