He is a fantastic coach and trainer, Bobby Fisher's second in his follow-up match with Spassky, and top ten in the world (1) mid-1990, and with another great coach and writer, Jeremy Silman, author of several great chess books. Three of all the time greats—Kasparov, Karpov, Ivanchuk—were in the top 4 when Seirawan cracked the top ten.
(1) olimpbase.org/Elo/Elo199007e.html