Walker was the MVP last summer at the FIBA Americas 18-U Championship in Argentina, leading Team USA to the silver medal. He was one of 17 players invited to the 19-U trials and would have been a virtual lock to make the 12-player roster. He averaged 13.4 points, five assists and 4.6 rebounds last summer for the 18-U team, which lost to host Argentina in the gold medal game.