Unless there has been advances in the technology in very recent times, they only measure distance travelled and the amount of sprints made etc. This info is used to keep an analytical view on the individual “red lines” of players. For example, the medical team will be aware that if player X has made 11 long sprints, 11 half pace runs and covered 11kms he is at his personal peak for muscle fatigue and is risking a soft tissue injury. To that extent, I think it’s a fantastic piece of kit. Professional sports have been using it over a decade.
I believe the next step will be to have wireless (obviously) pulse oximetry monitoring of each player, because monitoring actual heart rate during the game would be a better monitor of critical fatigue.
Advanced sciences in sport mean we have more powerful and athletic footballers than ever before. I think it makes the game a better spectacle, and of course, has helped us be as successful as we are over the last 6 years.