And now, Luetge is manager Eric Wedge's go-to lefty specialist out of the Seattle bullpen. Luetge didn't give up an earned run until June 19, and he's 2-2 with a 3.57 ERA and two saves.
So how is the 25-year-old so effective?
"He's got tremendous angle, particularly against left-handed hitters," pitching coach Carl Willis said. "He changes speeds with his slider, which is very good -- it actually turns into a curveball at times. He trusts it, which is huge.
"As the course of the season's gone, he's started to understand more certain situations -- certain left-handed hitters, where the runners are on base, when to give in or when not to give in, maybe move on to the next guy. I just think the command and ability to change speeds with his breaking pitches is huge, again, along with that angle."
But there's more to making the jump from Double-A to the Majors, and that's the mental side of the game, Willis said. In the big leagues, there's a bigger crowd, more energy and, of course, the best players in the game.
"When I first came up here, obviously you question yourself a little bit because you don't know what to expect, you've never pitched against these guys," Luetge said. "Once you get going, you kind of realize, especially when you see people you've faced in the past -- I've faced people in Double-A that I've faced here -- I'm like, 'Oh, these are the same guys I was playing against in the Minor Leagues.'"
Of course, there are also the All-Stars he has had to face. That takes mental strength to a new level. For instance, Luetge has faced Josh Hamilton four times.
How has Luetge dealt with that pressure? Well, he allowed a double, but he's also struck him out twice, making one of the best hitters in the game look foolish with his almost untouchable slider.
To help with the adjustment, Luetge has spent many hours in the video room, studying opposing batters. Now that he's more knowledgeable, Luetge doesn't spend as much time watching video, but he knows exactly what he's facing when he toes the rubber.
The slider, the mental confidence and the studying all make Luetge in the Majors make sense. And it's made for quite the rookie season.
"It's more than I can imagine," Luetge said. "Just coming here, I didn't know what to expect. I didn't know how I was going to handle myself, how I was going to do on the field, off the field. I think everything went great. We got two more weeks, so I'm not taking off any, but I couldn't ask for anything more for the first year."