Del Piero is not overrated. He had the skills to conquer the world. He knew it and the world knew it. That's one of the reasons why he did not deliver.
Ravanelli was certainly not overrated. He was an ok player, nothing more. After years of anonymity in the serie B he got the life opportunity to play for a big serie A club. He delivered despite being surrounded by much more talented and famous players than him. That's not being overrated. It's called to punch above your weight.