From Ken Davidoff:

Among those [Astros] who called Pettitte in recruiting efforts: New manager Cecil Cooper, ace Roy Oswalt, slugger Lance Berkman and veteran starting pitcher Woody Williams, who has a longstanding relationship with Pettitte and Roger Clemens.

Pettitte had to be somewhat tempted. But one underreported aspect of Pettitte's and Clemens' time in Houston was their frustration with the Astros' team culture _ that, unlike the Yankees, the Astros, in the two pitchers' minds, weren't 100 percent committed to winning.