Yankees manager Joe Girardi said that the moves were made in light of the club's day-night doubleheader on Saturday against the Tampa Bay Rays, necessitated by a rainout on Friday.
"That Scranton club, we've taken pieces from them all year, and they've found a way to get it done," Girardi said. "We've been dipping into their pitching staff the whole year."
Behind a starting pitching performance from Hughes, the Scranton/Wilkes-Barre Yankees secured an International League championship on Friday, routing the Durham Bulls, 20-2. Hughes allowed four hits while striking out 12 Bulls over five innings.
"The numbers were obviously very impressive," Girardi said. "The last time, he was throwing all of his pitches and throwing them well. His velocity was good. The overall report was very good with what he was doing."
Because of the rainout, Girardi said that it was a possibility that Hughes could slot into the rotation for a start against the Chicago White Sox on Wednesday, when he would be pitching on regular rest.
The 22-year-old Hughes opened the season in New York's rotation but was winless in six starts, faring 0-4 with a 9.00 ERA before a fractured rib sidelined him in late April.
He was 1-0 with a 5.90 ERA in six Triple-A starts before the International League playoffs began, but found another gear in the postseason, pitching Scranton/Wilkes-Barre past Durham twice. The Yankees plan to have Hughes continue pitching in the Arizona Fall League following the season.
"I think it was important for him to pitch the way he was capable of pitching," Girardi said. "He's done that down at Triple-A. Obviously he's coming up to help us and we'll see what his role is, but we want him to continue to mature."
Robertson, 23, was 3-0 with a 6.31 ERA in 21 relief appearances with the Yankees after being recalled on June 28. He was optioned to Scranton/Wilkes-Barre on Aug. 28, when the Yankees called up rookie Alfredo Aceves for bullpen help.
In his most recent Major League appearance, on Aug. 28, Robertson allowed a grand slam to Baltimore's Adam Jones. In three postseason relief appearances at Triple-A, he allowed three earned runs over 4 1/3 innings, walking four and striking out six around a pair of hits.
"We talked about [Robertson] being able to throw his offspeed early in the count for strike one," Girardi said. "Robby had done a pretty good job. He had a couple of rough outings, which makes his numbers look worse than they really were. We needed a pitcher at that point and we told him to continue to pitch and work on some stuff. He's done that."
Robertson was expected to join the Yankees in time for the first game on Saturday, though Hughes was not expected to arrive until Sunday.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.