Give this to MLS: They've shown a willingness to embrace technology. The latest piece is something called "micoach" which is being done as a partnership with Adidas and will allow coaches to track their players' movements, physical output and acceleration in real time. The technology will be unveiled during the July 25 MLS All-Star game, where the opponent is rumored to be Chelsea. All of this will be done using an accelerometer placed inside the players' boots.
The potentially seizure-inducing nature of that video aside, I could definitely see this being useful to coaches that are open to it. Some teams, like the Seattle Sounders and Portland Timbers, already employ much of the same kind of technology during training sessions.
Having the data in real time could certainly help coaches determine who's getting tired or who is simply not giving their max effort.