Pittsburgh ? Baseball’s June amateur draft is an inexact science, with far more failures than successes, and millions of dollars thrown at first-rounders 35 percent of whom will never play a game in the majors.

There is one time when a team is not expected to fail in the draft, though. That’s when it has the No. 1 overall pick, as the Pittsburgh Pirates do Tuesday on the first day of the two-day, 50-round draft.

The No. 1 choice is supposed to be a lock, a star of the future, a can’t-miss selection.

Yet sometimes they do miss; in 1966, the New York Mets took the long-forgotten Steve Chilcott with the No. 1 pick; Oakland, choosing next, got a future Hall of Famer named Reggie Jackson.

And the No. 1 pick in a very deep 1985 draft wasn’t Barry Bonds, as might be expected today with the benefit of 17 years of hindsight; instead, the Milwaukee Brewers selected catcher B.J. Surhoff in a draft that also produced Will Clark and Barry Larkin. Bonds didn’t go until the sixth pick, to Pittsburgh.

That’s why the pressure in on general manager Dave Littlefield as he oversees his first Pirates draft next week. Working on what would be a club-record 10th consecutive losing season, the Pirates simply can’t afford to make a mistake when they draft first overall for only the third time.

But with no clear-cut star such as last year’s No. 2 pick pitcher Mark Prior, who is already in the Chicago Cubs’ rotation the margin for error is high. And the effects of a bad draft, as Littlefield knows well from watching the Pirates play every day, can last year for years.

“In a perfect situation, you’d love to take the guy who is closest (to reaching the majors) but also has the best potential with the fewest risks,” he said. “Unfortunately, those kind of guys just aren’t out there this year.”

Strapped for cash a few years ago, several Pirates’ first-rounders were chosen not because they were the best player available, but because they were the best the Pirates could afford.

In 1998, for example, they took left-hander Clint Johnston when many scouts were projecting him as only a second-rounder; he has since left their organization and is still in the low minors.

This time, Littlefield said, the Pirates will get the best player. The problem is that scouts widely disagree on exactly who that player is.

The Pirates trimmed their list to three prospects Ball State pitcher Bryan Bullington, Virginia high school shortstop B.J. Upton and British Columbia prep pitcher Adam Loewen but all three have flaws lacking in some previous No. 1 selections.

A year ago, for example, Prior was a star at a major NCAA program, Southern Cal, and was widely considered one of the top college pitchers ever.

By contrast, the right-handed Bullington has excellent numbers (10-2, 2.11 ERA, 126 strikeouts in 93 1-3 regular season innings), but at mid-major Ball State. And he was roughed up in his first tournament start.

The Pirates have scouted Upton and Loewen extensively, but both are high-school players and thus are more of a risk than a college player such as Bullington.