"I didn't think it was going to be this bad at all. Getting the news yesterday felt horrible," Sampson said Saturday, sitting at his new locker in the Safeco Field clubhouse. "But the good thing was being here for that walk-off win. That was a special moment for me, too, being in uniform for my first time at Safeco.
"I'm just trying to find the good stuff in all this right now."
Sampson says the early prognosis is he should be back in time for Spring Training next year. And he said he's gone through the more-difficult Tommy John elbow surgery that forced him to miss his senior year at Skyline High School, so he figures he's mentally tough enough to endure another challenge.
But still, the idea of having his arm go out as he warmed up on the mound for the second start of his Major League career on Thursday in Detroit is one that would gnaw at any youngster trying to reach his dreams.
"I didn't really know what was going on," Sampson said of his final warmup tosses before he waved catcher Chris Iannetta out to tell him something was wrong. "I was kind of in shock. My arm didn't feel good at all. I threw my last pitch and I think my arm was trying to protect itself.
"I didn't feel it snap or anything, just total discomfort and I knew something was wrong. Which was tough, because I'm right there on a big-league mound and I would have done anything to stay out there. But I just couldn't do it."
Mariners manager Scott Servais acknowledged the injury was worse than initially expected.
"I feel terrible for him," Servais said. "He was really excited to get to the big leagues, you work your tail off and obviously playing for the hometown team and all that other stuff. Things happen unfortunately, but he's going to be out for a significant amount of time."
Sampson had about 20 supporters fly out from Seattle for his MLB debut at Fenway Park last Saturday and that bodes well for his upcoming rehab process.
"I have a good group of friends and family that are very supportive," he said. "They've seen me go through this before. It stinks, but I'm going to get through this."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011.
Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.