SAN DIEGO -- From his vantage point as the Giants' general manager, Brian Sabean has noticed the same flaw in Barry Zito's pitching that the left-hander himself has mentioned: an inability to throw his fastball where he wants it.

"He knows what he needs to do. It's just a matter of going out there and doing it," Sabean said Wednesday, one day after Zito fell to 0-5 by working a season-low 3 2/3 innings in San Francisco's 5-4 loss at Arizona.

Although Zito's fastball was traveling noticeably more slowly earlier in the season, Sabean said, "Velocity's not the issue. He's got plenty of velocity. There are guys who don't even throw as hard as him but have plus command."

Citing a baseball maxim, Sabean added, "Command and change of speeds is usually the secret to everybody's success or demise."

Zito's changeup and curveball, which remain potentially effective pitches, are diminished unless he can offset them with his fastball.

"It's the easiest pitch to throw early in the count for a strike when you need to go confidently at a hitter and get a ground ball," Sabean said.

Speaking of confidence, Sabean suggested that this also could be an issue for Zito after enduring repeated frustration.

"I'm sure he's battling [that]," Sabean said. "He needs to try to figure it out."