First of all it's been widely posted on that site that the player comparisons don't necessarily represent any type of ceiling/ability level but rather a player of similar playing style.
And "SIGNIFICANTLY"? Morneau had a .830 OPS in AA at the same age, that's better than what Lars has done this year (though last year...) but it's not like he was a .900 OPS guy by any means. And compared to the guy we're talking about trading him for, Gonzalez, he had a .719 OPS for TEX's AA and .777 OPS for FLA's AA.