The Arizona Diamondbacks have been an active team at the MLB trade deadline, and Merrill Kelly or Zac Gallen could be the next to leave.

Major League Baseball's trade deadline is scheduled for next Thursday, which means teams have less than a week to get their midsummer shopping done. The moves have already started, as the Mariners recently acquired Josh Naylor from the Diamondbacks while the Yankees acquired Ryan McMahon in a trade with the Rockies.

As the Arizona Diamondbacks prepare to face the Pittsburgh Pirates this weekend, the club made a pair of key roster moves that further signal their shift toward selling at the upcoming trade deadline. Right-hander Trevor Richards has been designated for assignment, while left-hander Brandyn Garcia has been recalled from Triple-A Reno.

As the July 31 trade deadline nears, the Arizona Diamondbacks are emerging as one of the more intriguing teams to watch. Despite ranking among the league's top five runs scored and home runs, Arizona is hovering around the .

Garcia is a 25-year-old left-hand relief pitcher the Diamondbacks just acquired from the Seattle Mariners as part of a trade that sent Josh Naylor to Seattle. Arizona also acquired right-hand starter Ashton Izzi in the deal, but he is in High-A Hillsboro to start his Diamondbacks career.

A lot of preparation goes into it." The Diamondbacks happen to employ a number of impending free agents who, in theory, could find themselves changing teams within the next week. Here are four worth keeping an eye on.