Armas, who was brought in as a fifth starter, struggled mightily in the first half of the season, when he posted a 0-3 record and a 8.69 ERA in 15 games.
But since the All-Star break, he is 4-2 and has lowered his ERA to 6.07. Armas has won four of his last six decisions, and in his last outing on Monday, he tossed six innings of shutout ball, limiting the powerful Brewers lineup to three hits in a 9-0 romp.
Armas has made some adjustments, including a leg kick that turns more toward the shortstop and adds lower-body torque to his pitches. Another is a modified arm slot that hides the ball from hitters an extra split-second.
"It's not easy when you have three years doing the same thing and you try to change," Armas said. "I'm just happy everything is coming together and hopefully, I'll just keep on going." Pirates' pitching coach Jim Colborn worked on changing Armas' mechanics.
"Honestly, I've seen it coming for awhile," Colborn said of Armas' resurgence. "There are the two elements in his delivery and then the third part, which finally came on Monday night, is confidence that it was going to work -- so he didn't have to be thinking about throwing a pitch and see what happens. It was just, 'Throw the pitch and know what was going to happen.' I saw the mechanical part coming for a good six weeks or more."
Armas is happy to be back in a groove after the mediocre start to the season.
"There's nothing I can do about the past," he said. "It's a good feeling to be finishing like this."
Bucs' manager Jim Tracy, who will send Armas out for another start on Monday in San Diego, gives the veteran a lot of credit for turning things around.
"Armas has worked very hard and he deserves an awful lot of credit," Tracy said. "He's been very attentive to what Colborn has been trying to do with him. His delivery is better, and I'm looking up there and seeing 90 and 91 mph, and I'm seeing life to the fastball and location with pitches."
Maholm improving: Lefty Paul Maholm, who has missed three starts with lower back pain, is close to returning to the rotation.
"Maholm threw a bullpen [session] on Tuesday," Tracy said. "It was really good, and the biggest thing that we are pleased about is ... he's been [able] to walk out there and get himself right back into the mechanical mode that he was in before.
"If everything goes cleanly, he will throw another bullpen on Thursday, a little bit more extensively, and he will pitch on Sunday in Houston."
Status quo: Outfielders Jason Bay and Xavier Nady remain out of the lineup. Bay has been suffering pain from patellar tendinitis in his left knee.
Nady is sitting out his eighth straight game with a mild concussion he suffered on Sept. 3, when he was hit in the head by a pitch from St. Louis' Andy Cavazos.
"On Tuesday, Nady was unavailable even for pinch-hitting," Tracy said. "I don't anticipate that changing as far as today's game. Bay is available -- he can hit, but we'll run for Bay. We'll look at both of them again on Friday."
Instructional league: The Pirates will send a total of 64 players to the Florida instructional league on Friday. Some of the Bucs' top prospects, including this year's No. 1 Draft pick, lefty Daniel Moskos, will participate.
Some other notable prospects include: right-hander Todd Redmond, right-hander Duke Welker, catcher Andrew Walker, first baseman Jared Keel, shortstop Brian Friday, and outfielder's Quincy Latimore and Austin McClune.
"It's a very important time," Pirates interim GM Brian Graham said. "It's a time to expedite the development of young players, and we outline for each player three things that we want them to get better at during the course of the five weeks. The main concentration is on those three areas, and hopefully, they leave there and they're a little further ahead by the time they get to Spring Training."
On deck: After an off-day on Thursday, the Pirates open a three-game series in Houston on Friday night at 8:05 p.m. ET. Right-hander Ian Snell (9-12, 4.00) will start for the Bucs. Houston will counter with right-hander Roy Oswalt (14-7, 3.41).
George von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.