McCarthy, who stayed behind in camp when the D-backs traveled Down Under, worked a spring-high six innings Wednesday, allowing three runs on six hits and a walk while striking out six. He finishes his spring with a 2.70 ERA and will make his regular-season debut against the Giants on Monday for the club's home opener.
As for Samardzija, he was scheduled to only go three innings Wednesday in his final spring start before Opening Day. He surrendered one run on four hits.
"I always give compliments to this team," Samardzija said of the D-backs. "It's a great battle every time and a great last tuneup before the season starts."
The right-hander, who will make his second straight Opening Day start Monday in Pittsburgh, said he's happy with his offspeed pitches, which he hopes will only improve once the Cubs leave the dry desert.
"The splitter will get better as the season goes along and the more north you get," he said.
The D-backs jumped on the board first in the second inning when back-to-back hits off Samardzija from Martin Prado and Miguel Montero to start the frame led to an A.J. Pollock sacrifice fly two batters later.
The Cubs answered to snatch the lead in the top of the fourth by hanging a two-spot on McCarthy, stringing together three hits in the inning, including RBI knocks off the bats of Nate Schierholtz and Welington Castillo.
Trailing 2-1, the D-backs went ahead for good in their half of the fourth courtesy of Trumbo's opposite-field, wind-assistant two-run homer to right field off Cubs left-hander Chris Rusin.
After tacking on two more runs in the fifth, the D-backs launched three homers in the sixth to break the game open. Rusin, competing for the fifth spot in the Cubs' rotation, was charged with nine runs on 10 hits over 2 2/3 innings.
After a sluggish performance at the plate against the Dodgers in Australia, the D-backs hope their offensive outburst Wednesday will set the table heading into next week, when the regular season resumes.
"This is what the doctor ordered right here," D-backs bench coach Alan Trammell said. "We hope that we continue swinging the bats well. We need to be able to sustain rallies and do those things, so that was very encouraging. We've been waiting for that for a while."
Up next: Hoping to secure the fifth spot in the club's rotation over Archie Bradley, Randall Delgado will take the mound Thursday afternoon in Goodyear, Ariz., at 12:05 p.m. MST against the Reds in one of the D-backs' split-squad games. Starting the other contest at Salt River Fields vs. the Indians at 1:10 p.m. MST will be Wade Miley, who took the loss to the Dodgers on Opening Day in Australia last week despite pitching well in his five innings of work. Miley is slated to start the D-backs' second home game of the year.