Kevin Towers is an outspoken proponent of a strong bullpen, and on Monday he once again put his money where his mouth is.

The Diamondbacks announced the signing of closer J.J. Putz to a $7 million contract extension through 2014, a source with knowledge of the deal said, a move that means all three of the D-backs' late-inning specialists -- Putz, David Hernandez and Heath Bell -- are under contract for the next two seasons.

Putz is due $13.5 million, Bell $13 million and Hernandez $3.25 million through 2014. To put that in perspective, the D-backs' three most expensive starting pitchers -- Ian Kennedy, Trevor Cahill and Brandon McCarthy -- will make only slightly more than that the next two seasons, depending on how Kennedy's first two arbitration years play out.

Putz, Bell and Hernandez have closed for playoff teams in pennant races, and the lessons Towers learned with a strong bullpen in San Diego, led by Hall of Famer-in-waiting Trevor Hoffman, were not lost. Towers believes a strong 'pen not only shortens the game but also makes it easier on the starting pitchers in general and on young starters in particular. The D-backs are likely to have at least two young pitchers in the rotation this season from among Wade Miley, Patrick Corbin and Tyler Skaggs.

The additions of Putz and Hernandez were the first moves Towers made at the 2010 winter meetings, signaling the direction in which he would lead the D-backs. The addition of Bell and the retention of Putz, first by picking up his $6.5 million option for 2013 and then with the extension, only amplify his resolve.

"J.J. has provided much-needed leadership and stability for our bullpen the last two years. He has been an integral piece and helped set the foundation for our bullpen's turnaround, so we are excited to have him in place the next two seasons," Towers said in a prepared statement.

Putz, who turns 36 in February, had a career-high 45 saves in his first season with the D-backs in 2011 and added 32 in 2012, becoming the first pitcher in franchise history with back-to-back 30-save seasons. After junking a cut fastball that he played with the first six weeks of the season, Putz had a 1.42 ERA from May 15 onward, when he also had a stretch of 19 consecutive save conversions.

The D-backs had a franchise-best 3.28 bullpen ERA in 2012, which ranked 10th in the majors. In the year before Towers took over, the bullpen ERA was 5.74, one of the worst in modern major league history.