I think in the last 15yrs football changed. Football is faster more technical the big giant players have been sacrificed for smaller, shorter, very mobile lighter players. Nowadays players cover 13-15km easily in a game, I bet in the 80s hardly will players cover 9km. Now it favours guys that can run fast and run longer. So bigger guys will suffer
Also it eliminated specialists for generalists. Think of it, when did the requirement for a goalkeeper start including playing with his feet. Older keepers are just evaluated based on the saves they can make and reflexes now their ball playing skills is almost as important as shot stopping
Now Central defenders. Gone were the days when the job of a defender is to stop attack and boot the ball away, Now every defender has to be able to play from the back even if their defensive abilities suffer. Also rules of the games have changed, the tackles you shake hands over in the 80s will land you in jail now, Center backs were allowed to be slow and mean. Now they have to be as fast as everyone. Tactics changed too. Now its more dependent on space than before, thats why almost every top team will play a high line and have a 40yards free space between last defender and keeper. So pace is key.
For a DM before it was ability to tackle, now its your ability to cover space and pass(Busquets). The AM of old were hardly required to do any defensive work, they were the king just pass the ball to them and they will create chances with their brilliance and elegance, Nowadays they are expected to run and press. Wingers are not only expected to cross they are expected to be a major source of goals. The olden days winger got dropped to full backs(Jesus Navas, Young, Valencia)
Now to attack, This is where the 9 suffered because they couldn't cope with the pace, they got eliminated almost completely and the Support striker who had more ball holding skills, who can drop deep were made to bulk up and play as lone strikers, Most strikers for top clubs at the beginning of their careers were support strikers. Morata Lewandoski, Benzema Suarez, Aguero, Henry, RvP. Its not uncommon to evaluate strikers on how much they can hold up play, pass, play with their back to goal instead of the old fashioned fox in the box who just stick it in the net
Tactics also changed. 4-4-2 which was the preferred tactics then favored target men. Now a 442 will most certainly lose to a 443, 5231 or 451 because the 2 men in front wont even get the ball since the midfield will be outnumbered
Also football went more scientific not just based on natural abilities, modern techniques were introduced into training, diets and match analysis where every coach is using technology to gain some advantage. Before its common to see footballers drink and smoke. Mario Basler was a chain smoker, Old highlights of matches I have seen some players smoke on the sidelines. Nowadays you cannot, you are placed on a strict diet and training regimen.
Football changed and the target men were the major casualty