The final comparison I'll do is at the catcher position, where Mike Matheny will wear the mask in 2005 in lieu of A.J. Pierzynski.
I'll say from the start that this move was a strange one -- strange not only in the signing of Matheny, but strange in the amount of money Matheny received. Matheny will now make more money than he ever has in his career, coming off a season which saw his OPS drop 36 points (not to mention Matheny's never had a .700 OPS season in his career -- no, not once). Just for the fun of it, let's look at what Matheny and Pierzynski did head-to-head in 2004:
Pierzynski: .272/.319/.410, 11 hr, 19 bb, 27 so in 471 ab's
Matheny: .247/.292/.348, 5 hr, 23 bb, 83 so 385 ab's
Okay, not even close -- A.J. is a hands-down better offensive player, even after having his worst full season as a pro. Let's all get the idea of Matheny doing anything significant offensively out of our minds now, because it won't happen...unless maybe they bat him 3rd in front of Bonds (just kidding).
And it actually gets worse offensively, because the Giants wouldn't have had to go outside of their organization to downgrade offensively at catcher:
Yorvit Torrealba, career: .256/.322/.402, 12 hr, 45 bb, 90 so in 512 ab's
So, Sabean had a catcher already on his roster that has a career .724 OPS offensively, would cost millions cheaper, and yet went out and got a worse offensive catcher and paid him 3.5 million dollars a year.
Defensively, it's difficult to argue with Matheny's skills. He's won the Gold Glove for catcher in the NL the past two seasons, and had another GG besides in 2000. It's hard to equate exactly how much a good defensive catcher helps, but I'll go out on a limb and say that Matheny's defensive advantage over Pierzynski about makes up for the offensive advantage Piersynski possesses.
But how about Torrealba? This is a difficult one, because Yorvit just hasn't caught enough games to be seriously compared to Matheny. For what it's worth, both Matheny's and Torrealba's range factor and career fielding percentage are both very close, so one could say that Torrealba could be as good of a defensive catcher as Matheny, but it would be hard to prove until Yorvit was able to play a full season at the position -- something that does not seem possible with the Giants organization.
So, in essence, the signing of Matheny isn't a bad move in and of itself, but the amount he was signed for and the probability that the Giants already had as good of a catcher as Matheny (or better) on their team who makes millions less -- well, that makes it very questionable move.