Popular baseball gear companies like Mizuno and Rawlings make an old-time and hard-to-find style of pants called knickers. These pants end with an elastic band just below the knee. You just need to buy logo-less baseball socks that cover the exposed skin. Not all baseball socks go that high and socks designed for other sports, like soccer and football, often have a company logo sewn into the shin. Adult knickers are especially hard to find in stores. Your best bet is an order over the internet.
Get those socks on first, high and tight. Put your regular-length baseball pants on and slide each ankle-end up to just below the knee, bunching up some of the pants in the process. Now drop the waist of the paints to the floor, undoing the bunched-up pants in an inside-out fashion. Fold over the top of each inside-out pant leg in a 1-inch strip around the knee, tightening the pants' hold on your leg. Now pull the waist up, button your pants and do your belt. The pants should now be folded over neatly just below the knee, exposing your high socks.