Not sure about the patterns being deader now than in the 80's, the ball-boy's' patches appear as dead as the baseline so either it's the courts (or number of games per court) that have changed, or his hypothesis needs to explain that as well.
If you look in the center of the court you will notice the wear patterns. He explains that in the 80's there were more players rushing the net and relying on agility vs. raw power from the baseline.
The grass patterns say technology is changing the game. Same with Golf (distance) and Basketball (height). Haven't seen it in football or baseball though.
