"We just need arms," Yankees manager Joe Girardi said. "It's unfortunate and it's part of the business that when you have options, you're part of that up and down. The big thing is we continue to call them up because we believe in them. It had nothing to do with performance. It had everything to do with [the fact that] we need innings."
Girardi said that he could use Mitchell as either a short or long man; Mitchell had initially been scheduled to start Sunday's first game, but the Yankees scratched him in favor of giving the start to left-hander CC Sabathia amid concerns about their bullpen.
The 25-year-old Smith was 8-0 with a 2.07 ERA in 16 games (15 starts) at Triple-A. Girardi said that he would be used in long relief, capable of throwing up to 100 pitches. A 14th-round pick by New York in 2013, Smith would be the 12th Yankee to make his Major League debut this season.
In Saturday's game, Holder held Boston to one hit over three innings, taking over for Adam Warren in the 11th inning. It was the second time Holder has delivered in a lengthy contest this season; he also worked three scoreless innings in an 18-inning, 5-4 win over the Cubs on May 7 at Wrigley Field.
"One pitch at a time and see where it goes," Holder said. "I was ready to go back out and do whatever I could to help the team win. A game like that, just battling back and forth and both teams playing long, hard baseball, it's fun to come out on top."
Making just his second big league appearance of the year, Heller picked up the victory by working the final two innings, striking out three around a walk. Heller's outing came after a long layoff; his most recent Minor League outing had been on July 6 vs. Buffalo.
"In the Minor Leagues, I pitched in a lot of close games, but it's kind of tough to simulate the adrenaline that you get in a game like this," Heller said. "I think I was trying to be very conscious of that and stay under control as much as possible. It's just what I kept reminding myself; 'Stay under control, but stay aggressive and pound the zone.'"
German, Mitchell and Smith might not have to wait long for their turns to contribute. Girardi said that he did not know if he could call upon Dellin Betances or Aroldis Chapman in the doubleheader, and would not use Warren for a third straight game coming off an injury.
On the position-player side, Girardi said that his biggest concern is fatigue, which is why he only plans to play Starlin Castro, Brett Gardner and Chase Headley in one of the games.
"Split doubleheaders are difficult," Girardi said. "They're especially difficult after you play 16 innings the night before."