HOUSTON -- Bobby Heck has put in a ton of work since taking over the Astros' Draft four years ago, but his biggest test lies ahead, when he will be expected to find an impact Major League talent with the No. 1 overall pick in next week's First-Year Player Draft.

Heck, the Astros' assistant general manager and director of scouting, has four Drafts under his belt with Houston and so far those have produced four Major Leaguers, including starters in catcher Jason Castro and right fielder J.D. Martinez, and there is more talent on the way.

With the Astros having the No. 1 overall pick for the first time in 20 years, Heck's next assignment is his biggest yet.

Because of the job he has done drafting players in the past four years and the series of trades made at the Trade Deadline in 2010 and '11, the Astros have dramatically improved a Minor League system that two years ago was the lowest ranked in baseball.

Having the No. 1 pick on Monday night represents an opportunity to make a huge stride forward in that regard, and the importance of it isn't lost on Heck.

"The biggest thing that comes with it is an extra opportunity," he said. "You get the first pick out of everybody. Every player gets to you. You're not relying on what other teams do in front of you. Every first-round pick is important, but it's really just the opportunity to get the player you want."

Coverage of the opening round and Compensation Round A will be aired by MLB Network and streamed live on MLB.com at 7 p.m. ET. Rounds 2-40 will also be streamed live on MLB.com on June 5-6.

Unlike recent years, there isn't one player who is a clear-cut choice to go No. 1. Some scouts favor college pitchers, like Stanford's Mark Appel, while others are in love with the tools of Georgia high school outfielder Byron Buxton. The Astros have been keeping their cards close to the vest as they consider who to take from a group of about five players.

"You can't take one year off in the Draft," Astros general manager Jeff Luhnow said. "You have to maximize your opportunity to bring in players, and in a year where you might miss your second-round pick, you better hope that your fourth- or eighth-round picks pan out. It's really a portfolio, and you have to have enough hits each year to keep the organization strong."

Prior to joining the Astros, Heck worked for eight seasons as the Brewers' East Coast scouting supervisor and was involved with restocking their farm system. Ryan Braun, Prince Fielder, Corey Hart and Rickie Weeks were among their draftees during that time.

Heck's first two selections with the Astros in 2008 -- Castro with pick No. 10 and high school pitcher Jordan Lyles with pick No. 38 -- reached the Majors quickly. Castro debuted in 2010 before missing all of last year with a knee injury, and Lyles made 15 starts for Houston last season at 20 years old.

Two of the Astros' most recent first-rounders -- high school shortstop Jiovanni Mier in 2009 and high school outfielder Delino DeShields Jr. in 2010 -- are in Class A this year. Martinez, taken in the 20th round in 2009, replaced Hunter Pence when Pence was traded to Philadelphia last year.

Outfielder George Springer, taken with the No. 11 overall pick last year from the University of Connecticut, is having a monster season at high Class A Lancaster and could be on a fast track to the Majors.

"This is a long-term process," Heck said. "It's good to see positive things happen, but I've been through a rebuild before, and I understand the time element and it's not always conducive in today's world.

"One [unproductive] Draft sets you back two Drafts, and there were a couple of those in 2000 and 2007. It made the task even more daunting, and it's building the foundation and building the walls and putting in the windows. It takes time, and we're starting to see we've made progress."

The decline of Houston's farm system was a gradual one that bottomed out in 2007.

The Astros struck gold with their first pick in the 2004 Draft, taking Pence in the second round. A year later, they selected Tulane two-way starter Brian Bogusevic in the first round as a pitcher, but wound up moving him to the outfield three years later. He currently starts in right field for Houston.

In 2006, the Astros drafted high school catcher Max Sapp in the first round, but he never got higher than Class A and retired following a near-fatal case of meningitis. That Draft did produce Major Leaguers in pitcher Bud Norris (sixth round) and third baseman Chris Johnson (fourth), however.

Houston lost its first two picks in the 2007 Draft for signing free agents Carlos Lee and Woody Williams in the offseason, and it failed to sign its third- and fourth-round picks, Derek Dietrich and Brett Eibner. The Astros' top signed pick was fifth-round outfielder Collin DeLome, who was released earlier this month from Triple-A.

That left the Astros without any players in their organization from the 2007 Draft. Enter Heck, who was hired by former GM Ed Wade in October 2007 and was given the task of trying to work magic.

"We haven't batted 1.000 and there's some you wish you could do over in time, but that does happen," Heck said. "Overall, with what we've added to the organization, I'm pleased with it. Still, we want more. I'm greedy in that way."