One of the oddest trends to emerge in the A's unusual past month is this: The team's most reliable starter in that time is Guillermo Moscoso, and the least, Trevor Cahill. Cahill was an All-Star last year, when he won 18 games. Moscoso was acquired in a minor offseason deal and was in Triple-A Sacramento's rotation until late May. What is the difference? Moscoso, who allowed two unearned runs in 4 2/3 innings Saturday night at the Coliseum, is doing a better job of throwing strikes. Cahill, who starts against the Giants today in the series finale, is struggling to find the zone. Cahill is 0-5 with a 5.67 ERA over his past seven starts, and his most recent outing was particularly poor - he walked seven Royals and struck out none in a 7-4 loss. The reasons for Cahill's struggles are up for debate. Manager Bob Melvin and pitching coach Ron Romanick believe that, with three members of the Opening Night rotation out of action, Cahill is trying to do too much. He's overthrowing sometimes. He's trying to be too fine other times. "At the start of the season, he was part of five Musketeers, and they were all feeding off each other," Romanick said. "Now it's just Trevor and Gio Gonzalez left. I told Trevor not to put all that burden on himself, don't try to do too much.