The Cubs often pointed to Carlos Zambrano's $91 million contract extension in August 2007 as the beginning of a marked change in his clubhouse and on-field demeanor. Zambrano began thinking of himself as the superstar nicknamed "Big Z," more than one player said, rather than the once-affable pitcher who earned that deal through hard work and talent. As one former Cubs official often pointed out, they don't include instruction manuals when they hand out megabucks contracts, so it's up to the individual to understand the responsibilities that go along with suddenly being rich beyond your wildest dreams. Starlin Castro, who signed a seven-year, $60 million deal last month with a $16 million option, heard the same whispers about Zambrano as everyone else.