Adam Everett is widely regarded as an amazing defensive SS. He got 688 chances last year in just under 1300 innings, about 4.7 chances per 9 innings. Or in other words, a little more than the number of plate appearances he'll receive. Now, consider that a very substantial number of those defensive chances are plays that anyone who's played high school baseball can and will make(pop-ups, sunday hops, easy force out throws, etc.), never mind a major league caliber defender. The sheer amount of chances that a defender gets to add value aren't near the amount of chances he gets at the plate. And even then, that ignores that defense is a 9 man affair, where you can bobble a ball and still flip to the guy at second for a forceout, or lose a ball in the lights/sun but the center fielder/second baseman comes in and grabs it. Offense has more of an impact than defense. There is no doubt of that, but defense can still add value. Plenty, actually. The thing is the ceilings we are talking about, and diminishing returns. The worst defender in the league can't really do that much damage. The best defender in the league...doesn't add that much value. Now the worst bat in the league can do plenty of damage, (and we may be talking about Izturis here if he puts up another .225/.275/.300 year) You get an average fielder and compare him with a fantastic fielder, there is improvement there, but it just isn't worth nearly as much as an average hitter compared to a fantastic hitter.