At times this season, his inexperience has been on display, but his potential is obvious, as well.
The 6-foot-4, 280-pound defensive lineman has been a regular starter for the Buffs (3-3, 0-3 Pac-12) in his first season with the program. The junior college transfer has 15 tackles this season.
"He's played well, but I expect so much more out of him and so does he," head coach Mike MacIntyre said. "It's kind of like a dimmer switch. All of a sudden it's going to be on."
Mulumba, who turned 25 on Tuesday, is from Helsinki, Finland, where he was introduced to American football. He then played the 2015 season at Diablo Valley College - where he was a teammate of current CU safety Kyle Trego. He then sat out the 2016 season.
Mulumba then earned a starting job in preseason camp. He's started five of six games, the only exception being the Sept. 23 game against Washington because he had to sit out the first half after a targeting penalty the week before.
"I'm progressing," Mulumba said. 'I feel like I'm playing every game better and I'm trying to play with better technique and execute better. I'm definitely getting better.
"The very first game (against CSU) I was a little bit nervous. Now I feel more ready. Everything is getting back to where I was."
It's only a matter of time before Mulumba's game takes another step up.
"Each week I see improvement and he'll keep making big, big strides," MacIntyre said. "He's played well, but he can play so much better."
Last week against Arizona was an odd one for CU senior receiver Devin Ross.
In the 45-42 loss, Ross didn't have any catches. He was targeted just once and dropped the pass.
Last year's leading receiver, Ross had caught at least one pass in 20 consecutive games before last week, and ad multiple catches in 17 of those games.
One of the reasons Ross didn't have a lot of targets is that he wasn't on the field as much as usual. CU found success with its run game against the Wildcats and often had two tight ends on the field as blockers. Using two tight ends takes receivers off the field, and Ross was often on the sidelines.
Co-offensive coordinator Brian Lindgren said the Buffs didn't anticipate using two tight end sets as much as they did. If they every do that again, however, they'll look more to get Ross the ball.
"Devin's a really talented player and we have to find ways to get him the ball," Lindgren said. "Moving forward, if you're in that set, that would be something you'd want to work him into, where he would have a package of plays that access his skill set there."
Wary of Nall
CU is well aware of what Oregon State running back Ryan Nall can do.
The 6-foot-2, 237-pound back had his breakout performance against CU two years ago in Corvallis, rushing for 122 yards on 20 carries in CU's 17-13 victory.
The Buffs held him to 35 yards on nine carries in a 47-6 win in Boulder last year, but they know how explosive Nall can be.
"When you get to play against somebody big and strong and physical, it's fun," CU linebacker Derek McCartney said. "That's why you play football. You like to hit people and that's what it's about."
In addition to Nall, the Beavers have talented backs Artavis Pierce and Thomas Tyner. Although OSU's run game hasn't been very explosive, MacIntyre said the Buffs can't take the group lightly.
"They're big and powerful runners," he said. "We're going to have to fit it up better, be more stout inside, hold the point a little better. We have to tackle those big guys. Get them on the ground. That's easier said than done."
A few other notes going into today's game against the Beavers:
- CU sports information director David Plati will see an amazing streak come to a close today. Dealing with some health issues, Plati did not make the trip to Corvallis. Plati had attended and worked each of the last 410 CU games, dating back to Nov. 19, 1983. Plati said he'll be fine, but his health issues prevent him from traveling.
- OSU has been outscored 270-116. The 154-point difference is by far the worst among Power 5 conference teams. Next worse is Kansas, which has been outscored by 76.
- CU receiver Shay Fields needs just one touchdown catch to reach 20 for his career. He's only four off the record of 23, set by Nelson Spruce (2012-15).
- Phillip Lindsay needs just 15 rushing yards to pass Rashaan Salaam for third on CU's all-time rushing list.
- CU has had three turnover-free games this season (including the last two). The school record for one season is four (1989, 1993, 2006 and 2011).
- MacIntyre is seeking win No. 40 in his career. He comes in with a 39-55 record, 23-34 at CU.
Contact staff writer Brian Howell at email@example.com or twitter.com/BrianHowell33.