Mariners' Luis Castillo is the key to making a break in tight-knit AL West

Seattle Mariners pitcher Luis Castillo is highlighted as a pivotal figure in the team's chances of breaking away from the competitive AL West division. The Mariners have not replicated their success from last season, but Castillo's performance is seen as the key differentiator in a tightly contested divisional race. The article suggests that Castillo's contributions on the mound could be the deciding factor in Seattle's fortunes going forward.