I'm sure it has to be a complete science, how to take care of the grass on football fields, in different climates and elevations. Especially after painting. I hadn't really thought of it..
Here's an article of how they flip fields, albeit from 2014. I would imagine that these Minnesota fields had/have artificial turf also, so completely different than natural grass.
Now that the Vikings and Gophers both play at TCF Bank Stadium, grounds crews are working hard to make sure the turf is painted properly for the right game. Over the course of the season, they'll have to flip the field 17 times. Several people have emailed WCCO wondering how this even happens.
www.cbsnews.com
But are the fields where the Jets/Giants and the Chargers/Rams play on, natural grass? If so, it would be interesting how they safely remove paint from the grass to flip a field, or to just keep the grass healthy.
Letting the grass die and resodding annually can't be the only way. Remember the Super Bowl last year (this Feb, in Arizona)) was played on newly sodded grass, and was supposedly quite a problem for the players.