Highlighting top Astros prospects for '10

We break down the top five prospects for each organization for 2010, taking into consideration: games, at-bats, innings and major-league service time. We expect these players to have rookie status remaining heading into next year.

According to MLB rules: "A player shall be considered a rookie unless, during a previous season or seasons, he has (a) exceeded 130 at-bats or 50 innings pitched in the major leagues; or (b) accumulated more than 45 days on the active roster of a major league club or clubs during the period of 25-player limit (excluding time in the military service and time on the disabled list)."

Note: Statistics are those at each stop in the minors this season and age represents how old they will be on opening day 2010.

Houston Astros

The Astros curiously selected a slew of high school prospects with their top picks in 2009, signaling an end to their win-now ways. They are now a team building for the long term again and there is some hope down on the farm. They ranked dead last in Baseball America's organizational prospect rankings a year ago, but some developing talent and some depth in the lower levels of the system should help them rise in minor league esteem even if they continue to slip in the major league standings.

1. Jason Castro, C, 22

The Astros have a wide-open gap at the catcher position right now that J.R. Towles has failed for fill for years now. Perhaps the Stanford product Castro can -- maybe even out of spring training. Castro hit a combined .300 with 10 homers, 73 RBI, 65 runs, three steals, a .380 on-base percentage and a .446 slugging percentage in 446 at-bats between high Class A and Double-A. He doesn't have the power of Matt Wieters, but few young catchers do. Castro's progress in his first pro season makes it likely he needs time in Triple-A, but barring the acquisition of a veteran in the winter, he has all the potential to take the starting catcher's job right away. Save for still rookie-eligible September call-up Buster Posey, there likely isn't a more intriguing long-term catcher prospect in baseball.

2. Jordan Lyles, SP, 19

The 2008 supplemental No. 1 pick behind Castro showed very well in his first full pro season in low Class A. He went 7-11 with a 3.24 ERA, .247 batting-average against and 167 strikeouts in 144 2/3 innings. It should earn him a ticket to high Class A, where it should be far more challenging for him. We don't expect to see him in the majors as a teenager, but a mid-2011 arrival is likely if he puts together another quality year.

3. Ross Seaton, SP, 20

It was quite a draft in 2008 for the Astros, as they selected Seaton in the third round out of a Houston high school. The local product didn't have as good of a year as Lyles, but he too was solid on the same team in low Class A. Seaton posted a stat-line of (8-10)-3.29-.261-88 in 135 2/3 innings and likely will be brought along at the same rate as Lyles, despite being a year older.

4. Collin DeLome, OF, 24

Hunter Pence never seemed to get enough prospect love from Baseball America and we have a sense DeLome could be the next Pence, albeit no center fielder. DeLome went .255-20-61-79-15 (.323-.465) in 467 Double-A at-bats and figures to open the season just one level away from a call-up. He does need to make better contact (141 strikeouts) and draw more walks (37), but his power potential makes the whiffs worth it at this point. Watch him closely for a potential Triple-A breakthrough in the first half of the season, or maybe even in spring training.

5. Jon Gaston, OF, 23

Gaston was among the minor league home run leaders for most of 2009, going .278-35-100-119-14 (.367-.598) in high Class A. We would be a lot more excited if it wasn't the hitter-friendly California League, though. Still, the 2008 seventh-round pick had a blockbuster first full pro season and will be a most-watched name down in the minor leagues this season. We figure he opens in the Double-A Texas League, but it is possible a serious power streak carries him to the major leagues before the end of 2010. It will be real hard to break in with Carlos N. Lee, Pence and Lance Berkman blocking him, though.

Best of the rest: Chris Johnson, 3B; Andrew Locke, OF; Koby Clemens, C; Polin Trinidad, SP; Brian Bogusevic, OF; Jay Austin, OF; Jiovanni Mier, SS; Brad Dydalewicz, SP; Juri Perez, SP; Sergio Perez, SP; Tommy Manzella, SS; Chris Hicks, SP; Brad James, SP; Leandro Cespedes, SP; David Duncan, SP; Tanner Bushue, SP; Jonathan Meyer, 3B; Tanner Nash, OF; B.J. Hyatt, SP; Brandon Wikoff, SS; Jose Vallejo, 2B; Federico Hernandez, C; Sammy Gervacio, RP; Gilbert De La Vara, RP; T.J. Steele, OF; Jose Altuve, 2B; Matt Nevarez, RP; Chia-Jen Lo, RP; Josh Flores, OF; and Luis Cruz, SP.

2009 rookies to exhaust eligibility: Bud Norris, SP; Felipe Paulino, SP; Albert Arias, RP; Yorman Bazardo, SP; Edwin Maysonet, 2B; and Jeff Fulchino, RP.

Last year's top five here: Paulino, SP; Johnson, 3B; Sutton, SS (traded to Reds for Jeff Keppinger); Trinidad, SP; and Colin DeLome, OF.

You can e-mail Emack your prospect questions to DMFantasyBaseball@cbs.com. Be sure to put Prospects in the subject field. Please include your full name, hometown and state. Be aware, due to the large volume of submissions received, we cannot guarantee personal responses to all questions.