Josh Vitters got his first big-league hit - a two-run pinch double in the seventh.
Other than that, it was a rough Tuesday night for the younger Cubs, whether rookies or two-time All-Stars - as the team lost for the seventh straight time since last week's trade deadline.
Left-hander Brooks Raley, who made his first big-league start just 19 hours after arriving in San Diego, struck out the first batter he faced, walked the second, but was done in by a four-run third and a three-run homer by Carlos Quentin in the fourth.
Manager Dale Sveum confirmed after the 7-4 loss what he said before: Raley will be on the mound again Sunday against Cincinnati and for at least another couple starts after that as the Cubs take an extended look at a handful of prospects.
Raley, who acknowledged being ``definitely nervous,'' sounded confident even after the rough, four-inning debut - and said he appreciates getting a longer audition than just a spot start.
``I'm going to try to take advantage of that,'' he said. ``I'm glad they gave me the opportunity. I think I belong here, so I'm going to try and get better.''
Brett Jackson, another prospect who debuted Sunday with the promise of a lengthy look the rest of the way, continued to struggle.
After getting a walk and two singles in his first three trips to the plate in the majors, Jackson hasn't put the ball in play since. He has struck out eight times in that span, including three times Tuesday, with a walk. He fell behind in the count 0-2 on six of the strikeouts.
Meanwhile, the suddenly senior member of this young core, Starlin Castro, has slumped badly since the team left Wrigley last Wednesday.
He's 0-for-19 since then, including a strikeout with two men on base to end the seventh Tuesday that sent him to the bench so angry he slammed his helmet loud enough to be heard in the press box.
``It's very tough,'' he said. ``It's the kind of thing that never happened to me. I don't know what's happening. I see the video last year and this year and it's not too different. It's just something that's happening in the game.
``But tomorrow's going to be different. Tomorrow it's going to be gone for sure.''