Whoever added the set didn't change it from "Standard" size, so the default of 2.5 x 3.5 was used and locked. Only Admin can adjust it now. Go to the set's overview or checklist page and enter an inaccuracy report (IR) to get Admin to adjust it.
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 10/25/2023). I have added a large portion of my inventory to the site, and currently have trading turned off (details are in my profile). I have (finally) unearthed my 2 very large boxes of Star Company minor league sets and they are available (email for details).