Danny Hultzen couldn't get loose on Thursday. (USATSI)

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Mariners prospect and left-hander Danny Hultzen was scratched from Thursday's start for Triple-A Tacoma after he had trouble getting loose before the game, reports Jon Heyman of CBSSports.com. The team is not terribly worried just yet.

Hultzen, 23, missed some time in spring training with a mild right hip flexor strain. The second overall pick in the 2011 draft pitched to a 2.78 ERA with 25 strikeouts and only six walks in 22 2/3 Triple-A innings last summer. He walked 43 in 48 2/3 Triple-A innings a year ago, including 14 walks in his final 8 1/3 innings.

J.J. Cooper of Baseball America notes that Hultzen's fastball has been at 88-90 mph this month. When the publication ranked the southpaw as the team's third-best prospect over the winter, they noted that he typically sits in the 90-92 mph range with a few 95s. It's still early, though, so Hultzen's velocity won't be a major concern once the weather warms up. Unless, of course, Thursday's problem is something more serious.