But you've got to start somewhere and Hannemann -- a 26-year-old rookie claimed off waivers from the Cubs earlier this month -- tallied the first homer of his career in Saturday's 6-5 win over the Angels. Marjama, a 28-year-old acquired from the Rays in an August trade and promoted to the big leagues for the first time as a September callup, followed suit with his own first home run in Sunday's 6-2 season-ending loss.
"I didn't want him to be alone," Marjama said with a laugh. "It's something cool. He's a really cool guy and we definitely clicked over the last month. I'm really happy for him. He's played excellent up here this September. Being around these guys is truly an honor and a great experience."
Marjama was making just his second big league start, and the home run came in his ninth Major League at-bat after working all month behind catchers Mike Zunino and Carlos Ruiz.
"He smoked that ball," manager Scott Servais said. "I like what I've seen from both those young guys who hadn't been in the big leagues before. Once they settled down and got in the flow of the game, their ability started to show. I think both those guys obviously will come to Spring Training with us next year and we'll see how they fit on our roster."
The Mariners added Hannemann primarily for his speed and defense after Jarrod Dyson was sidelined by sports hernia surgery. And now with Guillermo Heredia also on the shelf due to a shoulder issue that will require surgery next week, Hannemann got his third and fourth starts with the Mariners on Saturday and Sunday.
And the guy added for his glove wound up supplying an offensive highlight Saturday with a line-drive home run to right field, a well-struck ball that traveled an estimated 404 feet, according to Statcast™.
"I was surprised, more than anything," Hannemann said. "I'm not ever trying to hit home runs."
Consequently, he didn't wait around to admire the flight of the ball as it sailed well over the right-field wall.
"I'm a speed guy, a base-hit guy," Hannemann said. "So I'm going to run hard no matter what, even if it does go really far."
The Angels fan who caught the home run helpfully fired it back onto the field, so Hannemann already had the ball in his locker postgame without having to give up anything in return.
"We're all good," he said with a smile.
It was a nice moment for a youngster with 31 home runs in 457 Minor League games. Hannemann had six homers in 114 games for the Cubs' Double-A and Triple-A clubs this season while racking up 29 stolen bases.
"We haven't seen a lot of Jacob throughout the organization," Mariners manager Scott Servais said. "He's only played a few games here, but he does have some power in that one spot, kind of middle in, the left-handed hot zone, and he got the ball there and he juiced it."
Hannemann has yet to steal a base for the Mariners. He's only had three hits -- including Saturday's homer -- in his first 15 at-bats and was thrown out in his one attempt in his previous start Wednesday in Oakland.
He also made an error on Saturday, despite his selection as a Rawlings Minor League Gold Glove Award winner this year. But there are jitters when you get your first big league promotion, and the former BYU standout is working his way through those as he gains comfort in his first big league stint.
"My first at-bat, I was kind of shaking in the box," Hannemann said. "I'd never felt like that before. I'll calm down a little bit, kind of take a breath and just keep working hard and try to keep playing the game the way I always have."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB. This story was not subject to the approval of Major League Baseball or its clubs.