Rios was one very talented player in his prime. I've seen videos of him playing recently and his style has changed, he is much stiffer and almost seems to have devolved to become sort of a basic ball basher, forfeiting the creativity and artistry that made him so appealing to so many.
BTW there is also a new book in English about Rios out called "Marcelo Rios: The Man We Barely Knew." Very good read if you are or were a Rios fan. He was such a different player, competitor and character. Tennis needs a few more Rios types now to spice things up.
"He looked like he was trying to imitate Sampras when I first played him." Agassi in Facing Federer