As he nears the end of one of the worst opening months ever for a pitcher, the San Francisco Giants’ Barry Zito will head to the bullpen. It’s just the latest development in the downward spiral of a man who was once baseball’s best young hurler.

Since inking the largest contract for a pitcher ever at the end of the 2006 season, Zito has gone a paltry 11-19, including 0-6 this year. According to The San Francisco Chronicle, Zito is one of only three pitchers in the last 52 years to have that poor a start to his season.

It is a far cry from his heydays across the Bay in Oakland, where he began his MLB career.

Barry Zito burst onto the scene in 2000 as a mid-season call-up for the A’s. He appeared in just 14 games but was so effective that he placed in the top six in Rookie of the Year voting. He helped the A’s win their first division title since 1992.

The next year, Zito only improved and, at age 23, established himself as baseball’s newest phenom. His success was particularly impressive because he lacked a dominant fastball — his pitches rarely topped out at above 90 miles per hour. However, he had a lethal combination of off-speed pitches, including his renowned curveball, which was practically unhittable. Batters would swing hopelessly at balls that started at eye level and ended up below the waist.

Zito and teammates Tim Hudson and Mark Mulder led a daunting Oakland rotation that was comparable with few others in baseball. Zito, though, was the ace, and in 2001, his first full season in the majors, he placed in the top 10 in the American League in all the big statistical categories — wins, strikeouts, ERA, and so on.

But his best was yet to come: in 2002, Zito turned in one of the most dominant pitching seasons in the modern era. He won the AL Cy Young Award, as he compiled a phenomenal 23-5 record to go along with his 2.75 ERA and 1.134 WHIP.

In 2003, his win totals dropped off due to poor run support, but he maintained otherwise good numbers and went to his second All-Star Game.

But it was all downhill from there. Though just 26, Zito began to lose momentum on his pitches, which didn’t have much to begin with. His 12-6 curveball, his best weapon, no longer dropped as low — or as quickly — as it had previously. Simply put, batters started to figure the young ace out, and he could no longer control games like he used to. He had a hard time winning; his ERA went over four; and his strikeout totals started falling.

The writing was on the wall: despite a brilliant start, Zito simply did not have the pitches to be a consistent, overwhelming pitcher for his entire career. And there was the question of whether his arm could last — since his early twenties, he had thrown over 200 innings a year. He could still pitch, but he no longer belonged at the top of the rotation.

Zito had a bit of resurgence in 2006, as he retooled his pitches fairly effectively. But his numbers were still a far cry from those of old. Zito was becoming, at best, a slightly above-average pitcher.

But that being said, he was still the best hurler in an otherwise weak free agent market that off season. Two general managers in particular — the New York Mets’ Omar Minaya and the Giants’ Brian Sabean — made hard pushes for Zito. When it seemed that Minaya had the inside track toward landing Zito, the overzealous Sabean gave the pitcher an offer he couldn’t refuse and Minaya couldn’t match: $126 million over seven years.

That’s not just ace-worthy money. That’s best-pitcher-in-the-league money. Zito wasn’t close to either.

From the moment he donned a Giants’ uniform, Zito disappointed. He was entirely inept in 2007, as he turned in perhaps his worst professional season. To top it off, he was facing National League hitters, who, as a whole, are undoubtedly worse than the AL sluggers he used to face.

And, this year, he has hit rock bottom, and the Giants’ management, which entrusted the franchise’s future — financially and otherwise — in him just a short while ago, has lost its faith.

Instead of being the staff ace, he has been the bane of a rotation that featured talented youngsters like Tim Lincecum and Matt Cain.

Instead of being the example for the Giants’ young guns, he’s now a cautionary tale both to pitchers and GMs alike of how a career could flame out after such a promising beginning.

Wyndam Makowsky is a freshman who could probably throw harder than Barry Zito at this point. Share your scouting wisdom with him at makowsky@stanford.edu.