As part of a three-team trade with the Marlins and A's, Towers landed reliever Heath Bell (Miami) and shortstop Cliff Pennington (Oakland) while parting with outfielder Chris Young, who ended up with the A's after the deal was completed.
While the D-backs still have a lot of money tied up in contracts with catcher Miguel Montero, outfielder Justin Upton -- who figures to be a trade candidate -- and pitcher Trevor Cahill, the team doesn't have a single free agent on the roster to deal with moving forward.
The D-backs also have taken care of some business early by picking up the $6.5 million club option on closer J.J. Putz. The team now has a deeper bullpen to better contend in the National League West in 2013.
Moving forward, the D-backs will look to add a starting pitcher, left-handed reliever and possibly a third baseman. They certainly have some interesting trade chips to offer if they decide to move Jason Kubel, Gerardo Parra or Upton, who could land the team a big haul if Towers decides to move the 25-year-old right fielder.
Teams can start signing free agents beginning after 9 p.m. MST on Thursday.
Towers, of course, isn't averse to trading. It was last winter when he obtained Cahill in a five-player deal with the A's. He also spent big on Kubel, signing him for two years and $16 million, and retaining second baseman Aaron Hill on a two-year deal worth $11 million.
Free agents: None (reliever Takashi Saito was recently designated for assignment).
Eligible for arbitration: RPs Matt Albers, Brad Ziegler, Brad Bergesen, Mike Zagurski, C Wil Nieves, SP Ian Kennedy, OF Gerardo Parra, INF Cody Ransom, 3B Chris Johnson.
Non-tender candidates: Bergesen, Nieves, Zagurski.
Club options: RP Matt Lindstrom ($4 million with a $200,000 buyout).
Mutual options: C Henry Blanco ($1.24 million).
Areas of need
Starting pitching: Who doesn't need pitching? The D-backs will look to add to the mix of candidates for the rotation. Kennedy, Cahill and Wade Miley each made 29 or more starts. There are several young pitchers waiting in the wings, but Towers might look to add a proven innings-eater to give the team more depth.
Left-handed specialist: The bullpen is deeper with the addition of Bell and with the team opting to retain Putz. But the D-backs will look for a lefty to balance the bullpen after Zagurski and Joe Paterson struggled in that role last season.
Third baseman: Towers would like to add some thump at the hot corner, though Johnson was a nice fit after the trade from the Astros last summer. He hit .286 with seven home runs had 35 RBIs in his 44 games with the team.
After an Opening Day payroll just a shade over $75 million, Towers has said the 2013 payroll could rise to the mid $80-million range. The D-backs have about $15 million in deferred payroll coming off the books as well, which certainly could create more wiggle room as the team goes about building its 25-man roster for next season.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.