It looks like the 68.6 is being measured straight north and south. There is a little east and west involved in the toss too. 15 yards east to west makes it 70.2 in the air. 20 yards east to west makes it 71.4.
Edit: By these dimensions:
https://www.sportsknowhow.com/wp-con...iagram-lrg.gif
it looks like it was about 16 to 17 yards east to west which would put it in the neighborhood of 70.4 to 70.7 in the air.