Zack Greinke heads to Houston amid a busy MLB trade deadline

A flurry of MLB players are swapping uniforms after Wednesday's trade deadline. Here are three takeaways from a busy day:

Astros up the up ante — The Houston Astros and New York Yankees have been competing for the best record in the American League all season long, but only the Astros made a significant move on Wednesday. And, boy, was it significant. Houston struck a deal with the Arizona Diamondbacks to land former Cy Young Award-winning pitcher Zack Greinke. The Astros paid a steep price, but Greinke bolsters a rotation which already includes Justin Verlander and Gerrit Cole. The Yankees don't have anyone of Verlander's or Cole's caliber to fall back on, making their lack of moves frustrating for fans.

NL East arms race — The Atlanta Braves and Washington Nationals both did what they could to improve their shaky relief corps for the final stretch of the season on Wednesday. Atlanta dealt for veteran relievers Shane Greene and Mark Melancon, to add to Tuesday night's addition of Chris Martin. Washington added a trio of relievers, as well, making moves for Daniel Hudson, Roenis Elias, and Hunter Strickland.

Creativity in the desert — The Diamondbacks' sit at 54-54 and trail the Los Angeles Dodgers by 15.5 games in the National League West. The perception was they were ready for a fire sale, despite only being three games out of the Wild Card. Instead, it seems they tried to build for the future while still remaining competitive this year. Losing Greinke will hurt, but they got a haul in return, highlighted by pitching prospects Corbin Martin and J.B. Bukauskas. In another surprising move, they sent their top prospect, shortstop Jazz Chisholm, to the Miami Marlins in exchange for talented rookie pitcher Zac Gallen, who should step immediately into Arizona's rotation. Finally, Arizona picked up starting pitcher Mike Leake from the Seattle Mariners. Leake isn't as good as Greinke, but he's a veteran that should provide stability.