It has now been confirmed by Jeff Nelson, Penn State's Assistant Athletic Director of Communications, that Penn State's spring football practice will begin Saturday, March 19. The delay from Wednesday March 16 is likely caused by two previously mentioned items.
First, the men's basketball team is in the NCAA Tournament for the first time in 10 years, and the athletic department likely did not want to detract any attention from the team. Though, should the men's basketball team beat Temple, they will play on Saturday in Tuscon, likely against San Diego State. A further delay for the football team is unlikely.
Second, as mentioned earlier today, Penn State's Pro Day is scheduled for tomorrow, March 16.
While many of the players (and fans for that matter) are excited to see the team back on the field, they will just have to wait a couple more days. The annual Blue vs. White spring game will still take place on April 16.