This is a silly question. No, athletes have not gotten worse in professional sports, the games have changed though.
The reason why teams don't run as much in MLB today is because of the fact that small ball has been proven to be pretty pointless in the era of sabermetrics. Playing Whiteyball is kinda pointless if you have guys that can deliver the same production in one swing. Strikeouts stink, but when you are able to make up for those at bats in the aggregate, then it doesn't matter as much. Earl Weaver saw this 50 years ago, it's just now backed by statistics. You also have to remember that once traditional astroturf disappeared, running became even more of an iffy proposition. During the astroturf/multipurpose stadium era, it was like running on a track, and fielding every batted ball was an adventure. If you had a ton of speedy guys that could hit the ball on the ground, you could easily stretch what would be routine singles into doubles. You also have to keep in mind that those stadiums were huge, which made power hitters even less valuable, because those parks limited homers.
That isn't the case today. The return to baseball only facilities mean that a power hitter can easily reach the seats now, when 30 years ago, a lot of these blasts would just be long fly outs, or at best an extra base hit.
The NBA has also been affected by advanced statistics. Guys shooting midrange jumpers are obsolete, because it is literally the most inefficient shot on the floor(outside of the long two pointer). Unless you are shooting a layup/dunk, you are better off hitting a three. Simple math: A good midrange shooter will connect on 50%+ of his shots. That means that in theory, that they will score 100 points per 100 shots(jumpshooters are rarely fouled in the NBA). A decent perimeter shooter will shoot in the 35% range. So, for every 100 shots they take, they will score 105 points.
The games changing are more a reflection of people knowing more about how baskets/runs are scored and less about the athletes themselves.
