WEST POINT, N.Y. — On the first day of classes at the United States Military Academy, he was clearly the big man on campus. In much of the basketball world, he's Coach K. Around here, he's Mike Krzyzewski, Army class of 1969. Krzyzewski returned to his alma mater on Monday with the U.S. national team, which toured the campus, ate lunch with cadets in the mess hall and held an open practice for military personnel and families.