"When we made the decisions that we've made so far, they were tough decisions with consequences," Cashman said on Thursday. "We're better because of those moves, but we're thinner."
Both Aceves and Hughes have excelled in their new roles, as Aceves entered play on Thursday allowing just three runs in his past 14 relief outings and Hughes owned an 0.81 ERA in 16 appearances out of the bullpen.
But the switch made it difficult to fill in earlier this month, when the Yankees lost Chien-Ming Wang from their starting rotation, with no definitive return date for the right-hander.
New York is also watching the innings tick off rapidly for Joba Chamberlain, who will take the mound on Friday having already thrown 95 2/3 frames.
"I still think there is some concern with our depth," Yankees manager Joe Girardi said. "I'm not saying that you necessarily trade for a Major League pitcher, but there is some concern if someone else goes down. There are some innings limitations on Joba, so that is something that is a concern.
"I don't think you can ever really be too comfortable with your rotation. That's such an important part of your club."
The Yankees called up Sergio Mitre from Triple-A Scranton/Wilkes-Barre, and the right-hander won his first start for New York on Tuesday, but the cupboards are now beginning to grow empty at the Minor League level in terms of immediate help.
Cashman said that if another starting pitcher went down, his internal choices would include Kei Igawa and Ivan Nova, neither of whom would prompt the Yankees to rush into a transaction. So Cashman said the Yankees would instead tweak their current Major League roster.
"Right now, if we didn't do anything and we had another problem, we'd be taking Hughes or Aceves out of the bullpen and into the rotation," Cashman said. "It's as simple as that. That's been talked about internally and externally."
The Yankees could have that luxury, because they believe bullpen help is on the way. Left-hander Damaso Marte was clocked as high as 93 mph in a rehab appearance on Tuesday at Triple-A and is moving closer to rejoining the big league team, though there is no definitive timetable.
In addition, Cashman rattled off the names of Edwar Ramirez and Jonathan Albaladejo as relievers who could help the Yankees down the stretch. New York is also hopeful that Brian Bruney has turned a corner as he attempts to progress out of what they have called "Spring Training phase."
Cashman said that he is not looking to acquire a bat as July 31 approaches. If the Yankees do anything more in advance of that date -- the acquisition of Eric Hinske from the Pirates last month was sort of an early Trade Deadline deal -- it will likely concern a hurler.
"Offense is not an area right now at all that I'm focused on," Cashman said. "We'll continue to look at the pitching. The obvious injury to Wang right now has hurt. Ian Kennedy's aneurysm has hurt. The transferring of Hughes and Aceves to the bullpen has taken away immediate choices for the rotation. There is a depth issue that is real."