SEATTLE -- After making a move to bolster the Mariners bullpen with the acquisition of right-hander David Phelps from the Marlins, general manager Jerry Dipoto will continue searching for help for Seattle's starting rotation between now and the July 31 non-waiver Trade Deadline.
But Dipoto acknowledged Thursday that doing so appears a difficult proposition, given the number of teams in the same pursuit.
"We have been ear to the street," Dipoto said. "We have talked to every team in the league regarding starting pitching and the demand greatly exceeds the supply. And as a result, you think we gave up a lot to get David Phelps -- the starting pitching market is particularly high in what the asking prices are and we're going to be realistic in what we can afford to let go."
The Mariners gave up four Minor Leaguers -- including three ranked among their top 22 prospects by MLBPipeline.com -- to get Phelps, a right-hander who will be under team control through next season.
Dipoto said Phelps fits what the Mariners were looking for, a quality pitcher who can help beyond this year. The same will be true of any starter they covet, particularly given what teams are seeking in return.
"The only time we are likely to move what we think are our premium prospects is if we're getting a guy we think fits in our rotation not just for one year and probably not a year and a half, but more along the lines of multiple years out," Dipoto said.
For now, the Mariners will take their chances with James Paxton, Felix Hernandez, Ariel Miranda and rookie Andrew Moore, while also moving veteran Yovani Gallardo back into the rotation to start Sunday after he pitched extremely well in long relief.
That means Sam Gaviglio is headed back to Tacoma, where he'll offer depth along with Christian Bergman and others. Dipoto sees Gallardo, an 11-year Major League veteran, providing similar potential to many of the pitchers available on the market if he can continue throwing like he's done out of the bullpen recently.
"The performance wasn't there much in the first half, but the stuff has always been there," Dipoto said. "Now we're starting to see the results. He deserves another opportunity. He earned it. He's one of our most-experienced starters. So rather than go out on the market and overpay for what we don't think is an incredibly likely upgrade, why wouldn't we first explore what we have in-house because that could be all the upgrade we need?"

Like many teams, the Mariners believe a quality bullpen can help ease the pressure on the rotation as well. And adding Phelps to a group that already has posted the lowest ERA in the Majors over the past 51 games further adds to that strength.
"He's been under-the-radar good," Dipoto said of Phelps. "He's versatile, can go multiple innings, he can start. He has real stuff, a mid-90s fastball with a well-above-average curveball and a cutter that has really become a weapon for him and allows him to face both lefts and rights. He's a nice guy to have on hand. And from what I understand, a real pro in the clubhouse as well."
One thing Phelps won't be is part of the rotation this year, though Dipoto acknowledged that his ability to compete for a starting role in the future was part of the discussion when the Mariners acquired him.