Moneyball question: What were the real motivations behind the Carlos Pena trade and its treatment in the movie?

and he was riding the pine alot.

Baseball America ranked him #5 prospect in MLB that year. He had looked good in Texas in September call-ups the prior year, and was widely viewed as ready to step right in and start in the majors. Texas was in rebuilding mode then, and we gave up a strong package of younger prospects for him*.

For all the fuss about training Hatteberg to be a 1B, the plan at the start of the 2002 season was for Peña to be the 1B. He started every game in April. For most of those games Hatteberg was the DH, though he had some days off with others rotated through the DH slot.

Peña got off to a good start, but after a few weeks started to struggle, and then continued to decline. The A’s stuck with him and persisted in starting him regularly, but toward the end of April he would occasionally be pulled at the end of a game for a PH, either Saenz or Hatteberg. I believe the first game Hatteberg actually started at 1B was May 11. A week later, Peña was sent down to AAA. The idea of Peña spending a lot of time on the bench is incorrect. He played in almost every game when he was in the bigs. There were only three or four days where he was on the bench. The reason he was sent down was precisely because he was still a good prospect and they didn’t want him wasting away not playing. Once it became clear he wasn’t going to be starting regularly for Oakland they promptly moved him to Sacramento.

The impetus for trading Peña, I think, was not any animosity toward him. It was that he was a strong trade chip. At the trade deadline the A’s were buyers. They wanted to win this year, and the needed another good starting pitcher. Peña’s value had dropped a little with his struggles in May, but he was still a young guy with a stellar record as a prospect. He still had value, but he wasn’t going to do the A’s any good in the current year, now that Hatteberg was settled in as the regular 1B. That made him a top trade chip for the A’s, so when they went out to get Lilly, he was what they had to give up**.

*We gave Jason Hart, Mario Ramos, Ryan Ludwick, and Gerald Laird for Peña and Mike Venafro. Hart and Ramos were better known at the time. Hart was our erstwhile heir apparent for 1B, and Ramos was seen as a likely addition to the starting rotation soon. Venafro was a veteran LOOGY.

**We gave Peña, Franklyn German, and Jeremy Bonderman (as a PTBNL) for Lilly, Jason Arnold, and John-Ford Griffin. Arnold was later swapped for Erubiel Durazo. Griffin was traded for Jason Perry, who was traded for Jack Hannahan.

cute little diary he was writing in 2002? That was before everyone had a Twitter feed and a blog, but Peña had some arrangement where every couple days he’d write a few paragraphs about what it’s like being the new kid on the team, and it would show up with the mlb.com news stories.

and fantastic summary from iglew regarding peña.