Let's take the defense argument out of this, because neither side is going to prove that Chavez or Tejada is a better defensive player..
Both players actually look fairly equal when checking out both their statistics. The only category that Tejada has dominated in is RBI's when he acquired 150 last year and 131 in 2002. Both have fairly equal SLG % and Chavez has a high OBP in 2 of the last 3 years.
I think it just looks worse now because Tejada is destroying the ball and Chavez looks useless.
Anyway, Beane isn't looking to great right now and yes you can attack the guy for keeping Zito and trading away Mulder+Hudson. Was Mulder at the height of his value at the end of last year? No. While Zito can most definitly turn it around now, he's not doing anything special. The important question to ask is did Billy Beane put his club in the best possibly position to win this year? I think certainly the answer is no, yes it's early, but I don't think this club can contend. Also, did Beane put his club in the best possible position to win next year? Who knows right now..
...Boston papers now and then suffer a sharp flurry of arithmetic on this score; indeed, for Williams to have distributed all his hits so they did nobody else any good would constitute a feat of placement unparalleled in the annals of selfishness. -Updike