Before Masahiro Tanaka's first outing since coming off the disabled list, Brian Cashman felt a tinge of uncertainty.

Tanaka was unimpressive in two Triple-A rehab starts, and although minor-league results by rehabbing major-leaguers can be misleading, it doesn't mean they're irrelevant.

"It's hard to put stock in the results, but it's also hard not to have in the back of your mind: Is there something else happening there?" Cashman said Thursday afternoon during an appearance on SiriusXM's MLB Network Radio. "But then he came right out looking the way he did against the Mariners. He was in total command."

Tanaka, coming off a right forearm strain and right wrist tendinitis that put him on the disabled list April 29, produced seven solid innings Wednesday in the Yankees' 3-1 victory over Seattle. He allowed one run, three hits (all in the third inning) and no walks, striking out nine and retiring the last 13 in improving to 3-1 with a 2.76 ERA.

Though the performance held a small asterisk -- the Mariners are one of the AL's worst offensive teams -- the afternoon allowed the Yankees to breathe a sigh of relief. Tanaka's fastball peaked at 96 mph and overall had the most velocity since before his elbow injury last July.

A Tanaka resembling the version who dominated in 2014 before missing 2 months because of a slight tear in his right ulnar collateral ligament would make the Yankees, the front-runner in a remarkably weak AL East, the prohibitive favorite.

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"He certainly was very impressive and something we were hopeful for," Cashman said. "Certainly the player that we acquired from Japan. So I feel really good when he's on the mound at the major-league level. He's very impressive so far and hopefully we can keep him out there."

Cashman addressed several other issues during the interview on Sirius.

Designating disappointing righthander David Carpenter for assignment on Wednesday left the Yankees with only two righthanders in their bullpen, setup man Dellin Betances and long man Esmil Rogers.

"I probably need to find a righthanded arm," Cashman said. "Not probably, I do need to find a righthanded arm for the bullpen at some point."

Cashman also said that while a significant acquisition at next month's trade deadline can't be ruled out -- "we do have powder if we want to use that ammunition to shoot at some point to pull down some big game" -- he sounded reluctant to part with top prospects to do so. "It's going to be hard for us to move those guys," he said, mentioning Luis Severino, Greg Bird and Aaron Judge, among others. "We do have an evolving system."

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