The average player is much better than before. Back in the day, football was more of a game, than a sport. Today, with all the money invested in it, the youth development programs, the specialized training. It's only natural for players to become better on the average.
It's just like anything else in life. The longer it stays around, the better it gets. More people playing, and just more people associated with the sport is what makes the players better.
Back in the day, players could rotate from position to position quite a bit. Today, you don't see it as much, each player has a certain role to play, and concentrates mostly on that. They have to become better this way.