McDonald pitched seven sharp innings, Garrett Jones and Pedro Alvarez each drove in three runs and the Pirates returned home from another winless roadtrip, snapping a seven-game skid overall with a 7-1 victory over the Florida Marlins on Monday night.
McDonald had his second brilliant home start since joining the team sandwiched around a poor outing away from PNC Park.
"Certain factors come into play on the road, just certain tangibles that you don't even realize," Alvarez said. "Just being at home, you're just a lot more comfortable and at ease. You've got the fans behind you -- that helps a lot, believe it or not."
Pittsburgh, which lost all six games of a six-game trip for the third time this season, is 13-48 away from home but a respectable 27-30 at PNC Park.
McDonald won his Pirates debut with six scoreless innings at home Aug. 8. He didn't make it out of the fifth in losing his most recent outing at San Diego last Wednesday.
"When he's on, he can cruise through his innings pretty quick," Pirates manager John Russell said.
Dan Uggla went 3 for 4 with an RBI for the Marlins, who fell three games under .500 and nine games behind in the National League wild-card race.
The Marlins, losers of four straight and nine of 12, held a 15-minute closed-door players-only meeting after the game.
"We talked about a lot of different things," Uggla said. "It doesn't take a genius to figure out we've been flat the last five to eight games. ... We have to take it upon ourselves as professionals and as a team to be more competitive, be more focused when we're playing and have more intensity. We've got to bounce back, even if something may not go right early on in a game."
The Pirates got two runs in the first against Florida starter Chris Volstad -- on Jones' sacrifice fly and Alvarez's single that scored Jose Tabata and Neil Walker. Volstad, a right-hander, then faced the minimum over the next four innings, retiring 10 of 11 batters at one point.
Volstad (6-9) was lifted for Taylor Tankersley in the sixth after he loaded the bases with no outs. Tankersley promptly gave up a two-run double to Jones, scoring McCutchen and Tabata.
Alvarez then followed with a single into the right-field corner, driving in Walker and Jones to make it 6-1.
Volstad gave up five runs on five hits and two walks in five-plus innings. He lost for the first time in five starts since being optioned to Triple-A for three starts last month.
"We've just got to pick it up a little bit," Volstad said. "Four in a row, we're a better team than that."
Making his third start with the Pirates since being acquired from the Los Angeles Dodgers in a deadline day trade, McDonald (2-2) pitched more than six innings for the first time in his career. He gave up a run and three hits, striking out six and walking two in improving to 2-1 with Pittsburgh.
"I think it's real important ... when you get a guy on the ropes, 1-2, 0-2 even 2-2 counts, to put him away right then and there," McDonald said.
Andrew McCutchen hit his 10th home run -- but only the second in the past month -- to center field leading off the seventh.
Uggla drove in Logan Morrison with a groundout in the fourth to account for Florida's run. The Marlins have scored only seven runs during their streak, during which they are 0 for 33 with runners in scoring position, including 0 for 6 Monday.
"I think we have the talent," Florida manager Edwin Rodriguez said. "I think [the players] know we should be out there performing better. But then again, I say this honestly, most of them are trying 100 percent."
"We just have to raise our intensity to a high level," Uggla said. "There's no doubt in my mind that all 25 of us in this room can do that. I'm expecting to see a different team tomorrow."
The Pirates have had four losing streaks of at least seven games this season; seven streaks of at least five consecutive losses. ... Florida rookie OF Mike Stanton, named NL player of the week early Monday, went 1 for 3 with two strikeouts and a walk. ... Pittsburgh C Chris Snyder had two hits after having only one in his previous four games combined.