"He was such a young and promising guy," League added. "You could see him doing a lot of things in the game of baseball. And for as talented on the field as he was, he was such a nice guy off the field. That's what makes this even harder to swallow.
"I hung out with him off the field, and he was one of those guys who always wanted to go out to dinner and hang out and have fun. Even though he was an outfielder, he'd come to our bullpen dinners, and we always had a good time with him."
Halman, a native of the Netherlands, was stabbed to death in the city of Rotterdam early Monday morning, and his younger brother reportedly was arrested as a suspect by Dutch police.
Halman played 35 games for the Mariners last season before returning home to get ready for Spring Training, where he would compete for a full-time job in Seattle's outfield. The team, which signed Halman as an amateur free agent in June 2004, considered him a versatile, fleet-of-foot slugger with a big throwing arm and even bigger Major League potential.
That potential, as well as a zest for life and a strong desire to improve as a player and a person, was cut devastatingly short Monday.
"Great, great teammate," said veteran infielder Adam Kennedy, who played with Halman in 2011. "Great guy. He was fun to get to know and fun to watch learn the game at that level. I know he'd been in the system for a while and learning and getting better, and he was real fun to be around.
"I talked to a few different guys this morning, and he was one guy everybody enjoyed talking to and playing with and a guy everyone liked to see do well. He had become pretty close even with some of the older guys, so it's no fun for anyone today."
The Mariners will now come together to figure out a way to recover from this, and on Monday, the heads of the organization offered their thoughts via statements.
"The Mariners family is deeply saddened by the tragic death of Greg Halman," Mariners chairman Howard Lincoln, president Chuck Armstrong and general manager Jack Zduriencik said.
"Greg was a part of our organization since he was 16 and we saw him grow into a passionate young man and talented baseball player. He had an infectious smile that would greet you in the clubhouse, and he was a tremendous teammate. Our thoughts and prayers go out to Greg's family."
Said Mariners manager Eric Wedge, who took over the helm of the club last winter: "I only knew Greg for a brief time, but I feel lucky that I had the chance to get to know him. He was a fine young man with a bright future. Greg had a tremendous energy about him, both on and off the field, that I loved. This is just tragic. That's all I can think, that this is so tragic and sad."
Those sentiments were echoed down the line, from Mariners of the present to teammates and officials of the recent past.
"It's a sad day for all of us," Mariners first baseman Justin Smoak said. "He was a good friend and teammate and somebody we all knew really well. It's a sad day when something like this happens. I think everybody is kind of shocked.
"I woke up at 7 o'clock this morning with a text message and couldn't go back to sleep. This is not something you want to hear. He was such a good friend and teammate. You never want to see something like this happen. We're all shocked."
Halman's eye-opening raw ability was one thing that struck everyone he knew, but his easygoing nature and eagerness to forge a special bond with each teammate will be an even greater part of his legacy.
Reliever David Aardsma, who played with Halman on the Mariners in 2010 and '11, is of Dutch ancestry. He said Halman, who spoke four languages, called Aardsma "Dutchy" and would try to teach him Dutch words.
"Every day I'd mess it up a whole bunch, but I'd try to get it right, and then I'd try to surprise him with something I'd learned," Aardsma said. "He was just a great guy.
"It's hitting me hard. The stories written right now should be how he's battling for a spot on the roster next year and had impressed the brass with where he belongs, not about this. Somebody special got taken from us way too early. I don't know the exact circumstances of what happened, but it's a tragedy for all of us and the Mariners family. It's a sad day."
Former Mariners manager Don Wakamatsu watched as Halman rose through the ranks of the Minor Leagues. Wakamatsu said he was waiting for one of his favorite players and people to hit the big time at the game's highest level.
"You take life for granted until something like this hits you in the face," said Wakamatsu, who's the current bench coach for the Toronto Blue Jays. "Reports we had were that he had a chance to be a superstar, and I loved the kid. I knew he was a guy that was going to get it. He had all the tools to be a great player ... he was just raw, but he had the work ethic and the desire and all the tools. He was one of those guys that if he had the at-bats and playing time, he had a chance to be a great player.
"Greg had just a great, bubbly personality. You get into coaching, you want to make an impact not only on a baseball career but a life in general. And then you open up the paper and read something like this, and it just rips your heart out. It's like losing one of your own children."
A host of Halman's most recent and former Mariners and Minor League teammates, including Mike Carp, Casper Wells, Shawn Kelley, Ryan Rowland-Smith and Adam Jones, took to Twitter to offer their initial reactions and thoughts to the death of their friend.
And the ripples of this tragedy were felt outside the Major Leagues, too. In nearby Tacoma, the site of the Mariners' Triple-A affiliate and where Halman was a Rainiers outfielder in 2010 and '11, the team offered its condolences via a statement.
"Greg was a huge part of the Rainiers during his time here in Tacoma, and played a pivotal role -- on the field -- in our run to the 2010 Pacific Coast League Championship. But far more important than what he did on the field, was his personality off the field," Rainiers president Aaron Artman said.
"He had a huge smile on his face, every day, and his enthusiasm was infectious. He just had a way about him that made our front-office staff and fans see a guy who clearly loved what he was doing. He was often first to raise his hand when the Tacoma community needed him, and in particular, spent a good deal of time visiting hospitalized children, which speaks to his character.
"We miss Greg, already, and our prayers go out to his family, friends, teammates and the Mariners organization."