In the trade to Kansas City, the Astros received Kevin Chapman and a player to be named later (whom Jeff Luhnow noted would be the "key component" of the trade).
Kevin Chapman (24 years old, 6'4", 210lb) was the Royals' 4th Round pick in 2010, and has been a reliever his entire professional career. In 54 games he has thrown 80IP, striking out 110, and walking 36. He spent 2010 at High-A Wilmington, and 2011 between Wilmington and Double-A NW Arkansas.
While the Orlando Sentinel said his fastball hit 96 while at Florida, Chapman said this, about his pitches:
On a good day my fastball is at 92-94, slider 80-83, change-up 83-85. On an off day I really just focusing on getting ahead of the hitters and keeping the ball low in the strike zone.
He missed the entire 2008 season due to Tommy John surgery, but "is now considered one of the better relievers in his draft class."
Looking at his FanGraphs page, there are some major inconsistencies with his ERA/FIP:
2010 ERA: 5.50
2010 FIP: 3.20
2011 ERA: 4.84 (High-A)
2011 FIP: 1.14 (High-A)
2011 ERA: 4.99 (Double-A)
2011 FIP: 4.06 (Double-A)
He has posted BABIPs of .339, .451, and .337 on his pro lines, so don't freak out when you see his ERA.