Most of the players mentioned here are not anywhere near under-rated. Just because they're not mentioned in the same breath as Messi, Pele, Maradona, Cruyff, Beckenbauer, Ronaldo, Maldini etc. etc. doesn't mean they're under-rated. Most of the players I've seen in this thread are known to be some of the best players in their position & a few others were at least recognized world class during their time.
Baggio? Batistuta? Figo? Rivaldo? Hagi? Redondo? Sammer? Puyol? De Rossi? Eto'o? Brehme? Romario? Come on. Bonkers. They're all known legends.
Very few mentioned here were/are actually under-rated.