As a veteran tennis player/fan, and if Hawkeye is being used the same way it is used in pro tennis, then yes, they must have found a way to geolocate the ball relative to the line to gain with enough precision (even in the midst of multiple tacklers -- don't know how that is accomplished) to do exactly that. Hell, they could even "ring a bell" as the line to gain is crossed, similar to how "OUT" is electronically called in real time as the tennis ball misses the line in a tennis match.
wow, super cool if they have figured this out