When Moneyball first came out, there was some discussion about the movie's omission of Hudson, Zito, and Mulder. It seemed to bug people that three of the best players on the team weren't credited with any of its success (and it still does, because a recent article I read made a comment along those lines, which is why I feel the need to address it). In my opinion, I think the omission of Hudson, Zito, and Mulder was acceptable (for the most part). Not because I don't think they were valuable, but because they weren't new. Moneyball focuses primarily on the changes the team experienced during the 2002 season. Yes, the A's trio won an impressive 57 games. But they won 56 games the year before. In other words, their performance didn't make up for the departures of Giambi and Damon. I think the same reasoning can be used for the downplaying of Tejada and Chavez. They produced 365 hits, 68 HRs, 240 RBIs, and combined for 9.5 WAR in '02 (according to baseball-reference). The year before, they produced 325 hits, 63 HRs, 227 RBIs, and combined for 9.2 WAR. So it's not like they filled the holes left by Giambi and Damon either.
Obviously those five guys were
important to the success of the A's (and they deserved some mention), but
if their performances didn't make up for the loss of Giambi and Damon,
then what did? Those five guys with Hatteberg and Justice shouldn't have been good enough to match those five guys with Giambi and Damon.
But they did. They lost their best player, yet finished with a better record. That
shouldn't have happened. Yes the A's had good players, but nothing epitomized the concept of Moneyball better than
replacing Jason Giambi with Scott Hatteberg and actually being more
successful. That's why it's the main point of the movie.