Good thread Totally agree with Redondo, Deisler and Koller.

But for leo franco, martin demichelis (I'm not sure why, but I hate him wearing the Argen shirt ) and nelson valdez, they are rated just fine. Neither underrated, nor overrated.

I would put another name into the list though, who I believe is the most genuine Most Underrated Award contender.

Joaquin - was bound to be a world class RW during his Betis days, he was set for much bigger fame with Valencia. But his career never took off to full flight, due to his underachieving Valencia team. Now he is starting to find his footing, though at 29 y.o surely there's not much left for him unfortunately. One of the biggest 'what if' story in Spanish football this decade.

Special mention:

A host of players played for Deportivo La Coruna earlier this decade like Makaay, Mauro Silva, Valeron, Tristan, Fran. A team that full of potential players, but lost its prestige significantly when Fran, Makaay and Irureta either moved on or past their primes, and when the team was hit by financial disaster. Their history is even documented inwiki.