Melvin said Quentin, the club's starting right fielder much of the year, would "obviously" be called up, as well as Hammock, a third catcher who can play the corner infield and outfield spots.
Bonifacio, the only player called up from Double-A, provides a speed factor the club did not have. The switch-hitter could be used to pinch-run or as a pinch-hitter leading off an inning with the kind of speed that Melvin compared to the Mets' Jose Reyes and some of the best runners in baseball.
"It gives us a little added dimension we haven't had before," Melvin said. "A lot of things he can help us with, but speed is obviously the reason we got him here because we haven't had that dynamic."
Murphy represents a second lefty in the bullpen, while Peguero's pitched well enough to earn a promotion after a pair of previous stints with the club.
Although Murphy and Bonifacio will make their Major League debuts in the heat of a pennant race, Melvin remained unconcerned since players have made their debuts all year, including everyday players Mark Reynolds and Justin Upton, who like Bonifacio came up from Double-A.
"We don't get much into that," Melvin said. "Player development thinks that they can handle the big leagues, and they've been pretty right on as far as that goes."
When Tucson manager Bill Plummer called Murphy into his office after Friday's game and told him he would be promoted, the left-hander was in complete shock.
After all, he did not even have a spot on the 40-man roster at the time.
"All the guys were jumping on me, real happy for me, so that was probably the neatest thing, how happy everyone was," Murphy said.
A Major League debut had to seem far off for a pitcher who compiled an ERA above 5.50 the last two years in Triple-A before lowering that number to 3.63 in 2007. Murphy, who was unavailable Saturday after pitching six innings Thursday, said things started to turn around for him after he worked on his mechanics in the offseason and Spring Training.
Although he's worked as a starter of late, Murphy does not expect a difficult adjustment in moving to the bullpen, which has been his primary role the past two seasons.
Murphy, who held lefties to a .214 batting average this year, provides the D-backs with a left-hander to team with Doug Slaten.
"The need for us is either long length from the left side of just having that second lefty, especially with Slaten pitching four days in a row, so a guy that has the ability to get right- and left-handers out with his changeup and breaking ball and another guy we can use down there for multiple innings," Melvin said.
Reinforcements to aid struggling 'pen:
With the new blood in the bullpen, Melvin will have the opportunity to lighten the load on some of the relievers he's relied on all season.
That could be helpful after the bullpen allowed 11 runs the last two nights, with the damage coming against the back end of Arizona's 'pen.
"It's just this time of the year, with as many one-run games as we've played, guys in the bullpen that are used in those types of situations this time of year certainly aren't feeling like they are in April, but that's just baseball and that's part of it," Melvin said. "To an extent, every bullpen is feeling the same."
A lighter load could help the struggling Tony Pena, who has given up runs in seven of his last 10 outings, including Friday.
Melvin said Pena's stuff is still there, but the command has not been as good at times.
Conor Jackson was out of the starting lineup Saturday, a day after being hit by a line drive on his left wrist. Jackson said he felt "all right" and would be available to pinch-hit.
Melvin said he planned on playing Tony Clark at first base either Saturday or Sunday, so with Jackson being a bit stiff, this game presented the better opportunity.
Reynolds got the start at third base a day after being hit by a pitch near the left elbow.
"There's some swelling in there a little bit, but not affecting what he's doing as far as swinging or anything, so he fought pretty hard to stay in there," Melvin said.
Pitching for a spot:
Melvin remained undecided as to how he would use the fifth-starter spot in his rotation after Eveland started Saturday.
The spot comes up next during Thursday's off-day, and Melvin could arrange his rotation to only need the No. 5 starter twice the rest of the season.
"We'll monitor today and then kind of go forward from that," Melvin said. "With the off-day, we do have the potential to skip if we need to do that. We'll just look at the way today goes. There's a lot of different factors."
The D-backs finish their three-game series against the Rockies on Sunday afternoon at 1:40 MST. Arizona ace Brandon Webb (14-9, 2.83 ERA) will take the hill against Josh Fogg (7-9, 5.10).