28 players currently have a higher rebounding average than Pau Gasol.
NBA.com:
36 players currently have a higher scoring average than Pau Gasol.
NBA - Statistics by Category - Yahoo! Sports
9 players currently have a higher rebounding average AND a higher scoring average. So if you're looking at a player by his combined scoring/rebounding numbers, then Gasol is 10th best in the league, which barely puts him in the top third. While that's still very good, I don't think it's championship-level good. Gasol makes a great complementary player but he doesn't lift a team to championship-caliber status. During his 5 full seasons with the Grizzlies, he never got them out of the first round of the playoffs.
CBS Sportsline ranks Gasol as the 32nd best player (statistically) in the NBA:
NBA Basketball Player Rankings - CBSSports.com
Then again, rankings don't always translate into team success. The only team with two players in the top 10 is Denver (Iverson at #4, Anthony at #7.) The only teams with players in the top 20 are Denver, Orlando (Howard at #3, Turkoglu at #20), Washington (Butler at #5, Jamison at #11) and Utah (Boozer at #13, Williams at #19.) The highest ranking Spur is Tim Duncan at #21, the highest ranking Celtic is Paul Pierce at #30 and the highest ranking Piston is Chauncey Billups at #49.