No, not really. The PS2 has a higher tie-in ratio. Partly that's because it's been out for a year longer. If you chopped off one-fifth of the PS2's game sales, you might get something comparable.
But still, I believe the PS2's tie-in ratio is higher. It's all about the third party games. When a game goes multiplatform, people tend to either purchase it for Xbox because they reasonably think it's the best version or they buy it for PS2 because...they're idiots.
No seriously, they buy it for PS2 because that's what they have. Plus, there are just a lot mor egames available for PS2 than either of the other consoles.