The ERAs in the starting rotation of the Houston Astros are ugly. Of Astros starters who have made at least 10 starts, Peter Lambert's 3.26 ERA is the lowest. Tatsuya Imai's 6.14 ERA is the highest. Imai's first season since coming over from Japan has been filled with more struggles than anything else.The trade for Mike Burrows from the Pittsburgh Pirates hasn't turned out great for the Astros either. But there's still time for the Astros to make external additions. Mike Axisa of CBS Sports wrote Monday that a three-time All-Star from the Seattle Mariners would be a suitable fit in Houston. "If the Mariners trade a starter, [Luis] Castillo is the obvious candidate to go because he's the oldest and most expensive," Axisa wrote. "They'll likely have to eat money to facilitate a trade (he's o