Tuiasosopo was informed of the promotion after the Triple-A Tacoma Rainiers' game on Sunday. But even before he walked into manager Daren Brown's office at Cheney Stadium, Tuiasosopo had a hunch some good news was headed his way.
"They had called Rob in before me, and he was smiling when he came out," Tuiasosopo said. "I kind of had a feeling what was happening, and when I walked into the office, [Brown] asked me what I was smiling about. I told him, 'I don't know.'"
Without further ado, Brown broke the news that the third baseman would be getting his first taste of the big leagues.
"I was speechless," Matt said. "I just kept smiling."
A shortstop in high school, the 6-foot-2, 225-pounder was moved to third base early in his career.
"It's been good," he said of the position switch. "There definitely is a lot of work left to do over there, but in the last couple of years I've definitely put a lot of work in. Every day I'm taking ground balls and just perfecting the craft there. I feel comfortable over there."
The 22-year-old earned the promotion by setting career highs in practically every offensive category. He batted .281, scored 87 runs, hit 32 doubles, two triples, 13 home runs and drove in 73 runs in 111 games.
He started slow but finished strong.
Playing some 40 miles from home wasn't that easy, after all.
"I think I put a little too much pressure on myself first off, being back home," he said. "I just knew I had to fight through the emotions and not feel sorry for myself. I had dealt with struggles before in San Antonio, and I remembered what that was like. It wasn't fun, but I continued to work hard, and I knew if I kept grinding it out, sooner or later, things would start going.
"It was fun being at home with the family. That also made it easier to have their support."
The family, headed by former Seahawks lineman Manu Tuiasosopo, had a sweet season-ending party.
"My family was there at the game [on Sunday], and it was actually my dad's birthday the day before," Matt said. "I waited until we got to dinner, and I actually wrote it in his birthday card, that I couldn't wait for him and the family to be in the stands at Safeco because I got called up.
"He screamed, and my mom started screaming right there in the middle of the restaurant. Everyone started screaming, and it was fun. Right after they had read the card I called [older brother] Marques and told him and my sister-in-law, and they were all excited."
The Mariners made room for Tuiasosopo on the 40-man roster by transferring Willie Bloomquist to the 60-day disabled list, effectively ending what could be the valuable utility player's final season with Seattle. He is eligible for free agency at the end of the season and probably will test the market for the first time in his career.
Johnson, who made his MLB debut on Sept. 4 last season, spent all of this season at Triple-A Tacoma, batting .305 with 30 doubles, nine home runs and 49 RBIs. Lowe, Morrow and Wells all spent time with the Mariners earlier this season.