During the years he was in Seattle at the beginning of his career, Griffey was right there with the all-time greats: Barry Bonds, Willie Mays, and Hank Aaron. This graph shows the cumulative Wins Above Replacement for those four players. At the age of 30, they are all very close to each other. Bonds, Mays, and Aaron continued to be great for many years after, while Griffey offered little to the Reds, the White Sox (briefly), and the Mariners (when he returned) over the last part of his career. It probably didn’t help his legs to play on the Kingdome turf all those years, and he ran into a few walls along the way, but he was among the best of the best when he played center field for the Mariners from 1989 to 1999.
*WAR graph courtesy Fangraphs.com