Jones, the team's first-round draft choice in 2003, who spent the first two seasons of his professional career at shortstop before making the full-time conversion to center field this season.
Jones was hitting .277 with 14 home runs and 55 RBIs in 82 games at Tacoma. But it's not his bat that the Mariners need now -- it's his glove, his legs and his improving instincts.
"I had [Kenny] Lofton early in his career," Seattle manager Mike Hargrove said. "Kenny made mistakes in the outfield, but he outran his mistakes. I don't know if Adam is going to make mistakes out there. But as long as they are aggressive mistakes, that's fine."
Jones was informed of his promotion on Wednesday before the Triple-A All-Star Game in Toledo, Ohio. He didn't appear in the game and flew to Toronto on Thursday, joining the team upon their arrival late Thursday.
Jones, who will turn 21 on Aug. 1, said he was as surprised by his advanced timetable as just about everyone else who figured the Mariners might let him spend the entire season at Tacoma.
"I told myself when I came out of high school that I wanted to be there by 22," Jones said. "All of this stuff came so fast."
Jones pushed his own timetable by playing well at every level. He started last season at Class A Inland Empire and hit .295. He earned a promotion to Double-A San Antonio, where he hit .298 in 63 games.
This season, Jones started slow at Tacoma -- offensively and defensively. His swing was a little too long, and he, understandably, had trouble initially with taking good routes on fly balls and making throws.
"Early on, I was trying to do too much, and then it just clicked," Jones said. "I told myself to hit the ball the other way. I was trying to pull everything. I started having great at-bats. I was more consistent in what I was doing. My average came up and the hits came in bunches. Anything that's thrown at me now, I feel like I can hit it."
The Mariners tried to make a go of using Shin-Soo Choo in center field after Reed broke his thumb. But Choo -- who hit .091 in 11 at-bats over four games -- wasn't the right fit in center field.
"Choo is not a center fielder, he's a corner outfielder and can play center field," Hargrove said. "We thought that with the way he was swinging the bat, we could bring him here, play him in center field and get his bat in the lineup. It just didn't work."
So now Jones will get his shot. Regarded as the top position player prospect in Seattle's Minor League system, Jones will get a chance to play every day.
"He's 20 years old and one of our top prospects, it doesn't do any good to have him sit," Hargrove said. "The whole idea is to bring him in here and play. With his speed in the outfield, hopefully he'll run down some balls we couldn't do otherwise."
Back again: Greg Dobbs is convinced that he's better suited to handle his third stint with the Mariners than he was his first two in 2004 and last season.
"The more time you spend up here, the more comfortable you become," said Dobbs, who was selected from Triple-A Tacoma. "Once you get away from being awestruck and the nervousness goes away, you can just play the game. I think every stint I've had up here has helped me."
Dobbs -- who can play first base, third base, left field and right field -- essentially takes the place of Roberto Petagine, who was designated for assignment last week. But unlike Petagine, Dobbs offers more versatility and a left-handed bat.
Dobbs, 28, was hitting .299 with seven home runs and 46 RBIs in 81 games with Tacoma.
Dobbs hit .226 in 53 at-bats in 2004 with Seattle and .246 in 142 at-bats last season with one home run and 20 RBIs.
Mariners log: To make room for Jones on the 40-man roster, Seattle asked for waivers on pitcher Jeff Harris for the purpose of giving him his unconditional release. Harris, 32, started the season with Seattle and had a 5.40 ERA in three games before he was optioned to Tacoma. Harris had experienced tendinitis in his right shoulder and was rehabilitating at the team's Spring Training facility in Peoria. On Thursday, the Mariners optioned Choo to Tacoma and outrighted catcher Luis Oliveros to Inland Empire.
On deck: The Mariners continue their three-game series against the Blue Jays at 1:07 p.m. PT on Saturday. Jamie Moyer (5-8, 3.50) faces Roy Halladay (12-2, 2.92). There's no local television for the game.