Check the jersey in cricket positions, not only standing upright. Raise the bowling arm fully, rotate through a batting stroke and reach overhead for a catch. The chest, armhole and upper sleeve should allow those movements without pulling uncomfortably across the shoulders.
For wicketkeepers, check the shirt in a crouch and while extending both arms. For batters, assess body length with the shirt worn as it will be on match day, and check long-sleeve cuffs alongside gloves. Use garment measurements for junior and adult players rather than relying on age or a familiar size label.