Was it a poor decision? It got Zambrano out of the game. And Dusty is known for racking up high pitch counts for his starters. IMO getting out of the inning with no runs allowed was way more urgent than chasing Z. At the same time, the Padres have one of the best defenses in baseball, a park that tends to keep balls in play and a struggling offense. There was no guarantee that the Cubs would pull Zambrano, a guy they struggled to hit all night.