Having been shut out of Baseball America's Top 20 Gulf Coast League Prospect list, the Astros put three on the Top 20 Midwest League Prospect list. Click the link (and subscribe, if you don't already to see the full scouting report, but here are the names with a money quote:
No. 2: Carlos Correa
Like Machado, Correa has the potential to be the rare offensive force
with plus power who can play on the left side of the infield either at
shortstop or third base.
No. 5: Lance McCullers, Jr.
Scouts speculate that he could help a big league club right now as a reliever.
No. 12: Vincent Velasquez
The lack of a consistent breaking ball is a concern, but some scouts
like him more than McCullers because he seems to be a safer bet to
remain a starting pitcher.