http://sfgate.com/cgi-bin/blogs/sfgate/category?blogid=21&cat=539He didn't do it because Oakland has a history of doing those things, they did that with field players like Giambi & Damon. They have historically built their teams through their farm systems and get what they can out of their players until they become free agents and then trade them away or let them sign elsewhere.
Jason Giambi contract offer
Giambi ended up walking away from the A's six-year offer, and that's a good thing for Oakland. He has had a couple of good seasons in New York, and this year is back to his old form -- dammit. But he was also a drag on the offense for two years while struggling with a mysterious intestinal parasite. The Yankees can afford to pay somebody for 7 years at $17 million a year in order to get four productive seasons. The A's don't have money to burn like that.