How much does age really affect top players?

Simply question really. I was thinking about guys like Nesta, Del Piero, Totti, and Ronaldinho. Even in their twilight years, they are/were still top players when they really put their mind to it. I understand for pafey players it might be a problem, but really, technical players dont have a problem. Del Piero for example was one of our best players between 08-12 even though he qas well past 30. He is tearing it up now in Australia, and while that is no huge feat, he could still play for Juve in my opinion and be probably our best forward outside of Tevez. So how much does it really effect them?

A lot.

The lack of Speed makes it difficult to get past a Player. The lack of Stamina renders mobility. Reflexes aren't the same either after one reaches their 30's Strength is rarely lost. The ways to make up for lack of Physicality is to focus on every other attribute not related to Speed and Stamina.

There are exceptions of course.

Freaks like Giggs and Ze roberto can still play and perform well past their 30's so i don't think age affects players that much as long they look after themselves and keep fit.

Watch Buffon 10 years ago and watch him today. That should anser your question.

Zanetti is a prime example. The man is eternal.

Depends entirely on the individual.....

Some lose more and can't adapt than others as they get older.

For example Totti adapted to his age and is still one of the best around in his position.

Where as the likes of Cambiasso nose dived pretty quickly as he approached his early to mid 30s.

They never really lose technique, but age affects the time it takes to recover from injury, the incidence of injury, and their physical strength and endurance to withstand a full match. I'm not sure how much of it is biological and how much lifestyle, and it's likely to depend on the individual, but I suspect professionalism has a huge role to play in the decline of individuals.

Depends on the style of player, how well they look after themselves, how much football they play, how many injuries they pick up, severity of injuries, the body than they're born with. I was never good at biology but surely some people have different muscle, bone or body types?

there is always an exception, but typically and obviously when you reach a certain age, depending on which position you play you generally start getting worse...
whether it is vision, speed, stamina, all of the above or other.
Players like Ronaldinho or like the other examples you say are all worse then they were 5 years ago.. they had so much talent that even when they get worse they are usually better then the average player.

 Totti hit double digit in both assisting and scoring last season , 12, 12   but i guess he is a different case . The god of football is immortal

It really doesn't effect highly technical players that much. Players like Silva and Pirlo, will still be good even at 38.

What age affect the most is players that rely on pace. And then they lose their speed, and don't look half the player.

But most players that never relied on pace and have good technique seem to last a long time.

Today's 30 is very different from the 30 of the past.