Initial reports on the TV broadcast had it at 446 feet. Last night, articles on MLB.com and affiliated sites were calling it 414 feet.
Today, however, HitTracker has posted a correction and is now telling us that it flew a whopping 476 feet!
That's good for the best in the majors so far by more than 20 feet and 40 feet more than the third best. It would have been good for 4th best in the majors all year last year.
Even more impressive, Heyward's home run was hit at only 22.6 degrees, far less than the optimal angle for hitting for distance and outside of the typical range for homers given by HitTracker (between 25 and 45 degrees). If he'd given it a little more loft off the bat, that ball would have gone even farther.
Another metric for measuring home run power is the speed that the ball comes off the bat. Heyward's shot was a 120.9 mph screamer which would be good for the second fastest hit all last year and would be top five in any year since HitTracker has been keeping records in 2005.
At age 20. On his first big league swing.