And they certainly would not have led the league in one-run victories with 32 if not for the bullpen, particularly Tony Pena, Brandon Lyon and Jose Valverde.
Melvin has used those three to pitch the seventh, eighth and ninth innings, respectively, with Pena sometimes coming in as early as the sixth. It's a recipe that has shortened games for the D-backs, and the trio's success has been a comfort to the team's starters.
"When you come out of a game with a one- or two-run lead, you have complete confidence in those guys," starter Doug Davis said. "They've done it all year long. I'm not saying they're perfect, but they've been pretty much the best in the league, and you can't ask for anything more than that."
The same can't be said about last year's bullpen, which was an Achilles' heel for a team that struggled to stay in the NL West race until the final 10 days of the season.
After looking at the situation, the organization decided the problem wasn't necessarily the relievers, but the fact that the starting rotation didn't pitch enough innings, which overtaxed the bullpen.
So last August, Arizona general manager Josh Byrnes acquired starter Livan Hernandez from the Nationals, and in the offseason he picked up Davis from the Brewers. Both pitchers are known as innings-eaters and Hernandez worked more than 200 innings this year, while Davis checked in at 192 2/3. Combined with ace Brandon Webb, who threw 236 1/3 innings, they reduced the burden on the bullpen.
That in turn allowed Melvin to use his relievers in defined roles -- Pena and Lyon splitting the seventh and eighth innings and Valverde coming in the ninth.
"Performance-wise I think the thing that has really helped them is that Bob has kept them in consistent spots and consistent roles," D-backs pitching coach Bryan Price said. "Guys know when they're going to get the ball, guys know they're going to get time off when they need time off."
Valverde, who started out as the club's closer last season before struggling so badly after a hot start that he was demoted to Triple-A Tucson, led all of baseball this year with 47 saves in 54 opportunities.
Part of his improvement can be traced to him limiting his pitches to just a mid-90s fastball and split rather than trying to mix in a slider or two-seamer as he did last year. Another reason for his turnaround, though, has been his ability to bounce back after poor outings. In the past, it seemed to sap his confidence, but this year, he's shown no carryover after a blown save.
"I think what he went through last year, getting sent down, losing his role, made him tougher mentally," Melvin said.
Pena, Lyon and Valverde get most of the attention, but the contributions of Juan Cruz and Edgar Gonzalez can't be overlooked.
Cruz has been a band-aid of sorts in the bullpen. The possessor of an electric fastball, Cruz has pitched in long and middle relief as well as a setup role when either Pena or Lyon were unavailable.
Gonzalez on the other hand started the year in the rotation, but after being moved to the bullpen, he's worked in long relief as well as getting some spot starts. While his ERA of 5.03 is high, he has an 8-4 record, and more importantly, he has helped eat up innings when needed in blowouts to save the rest of the relievers' arms.
"We are all just out there trying to do what we can do," Lyon said. "No one is trying to do too much. We're all just trying to get outs. It's just fun to watch these guys and watch everybody go about their business. If someone has a bad game, they just tee it up the next day and come in with the same attitude."
The D-backs' ability to shorten a game to six innings with the presence of Pena, Lyon and Valverde could turn out to be a difference maker in the playoffs.
"Everyone talks about starting pitching in October, but I don't know that you win series unless your bullpen is on a nice roll," Melvin said. "It might be the biggest absolute for success in October. I think our group is as well equipped as any to pitch well in big games. They have all year."