It's rare that a Division II athlete gets calls from the top teams in the country clamoring to sign him, especially when he doesn't get invited to the national scouting combine held in Indianapolis.
This last year, only 11 players from Division II football heard their names on draft night. Many more signed undrafted free agent contracts and even more participate in rookie minicamps as tryout athletes. Most of those players are merely bodies that other rookies are asked to practice against, but occasionally there are surprises.
Thielen took a longer road than most to get to the NFL, and participated in one of the many regional combines around the country in order to get noticed. He was one of the 218 players selected from those regional combines to be represented at the Super Regional Combine, an event that produced 14 players to play in an NFL game last year, although over 50 sign contracts each year.
Atlanta, Green Bay, Jacksonville and San Francisco ultimately approached Thielen and his agent, some asking for film to get a closer look at him.
But after the draft was over, it was the Vikings that Thielen chose.
"I mean, it's where I wanted to be as a little kid growing up," he told me. "Just being a Vikings fan watching Cris Carter and stuff like that. It's always been a dream of mine and I'm just happy to be here."
Thielen was confident in his performance at the Chicago Regional Combine, one of eight such testing events held throughout the nation.
That doesn't mean he wasn't anxious, however.
"I felt good about it, but definitely nervous. That was my lifeline, really. It was my last chance to make it. My only chance to show what I got."
He did extremely well in that showing, putting up a 4.45 40-yard dash and a 6.77 three-cone drill. There's a youtube video of him running the three-cone even faster, at 6.39 in his training facility.
This speed surprised a number of observers, and running at a high level with agility is always a coveted talent. He was dominant in his time at Minnesota State—Mankato, so I asked him if it was fair that others were startled by his quick times.
"I've heard it my whole career-high school, college, so it wasn't surprising to me," he said of the coverage. Craving a chance to prove it, he was given the opportunity to work with those tools when invited to the Vikings minicamp.
Showing up there, Thielen was in a tough spot, as three relatively well-reviewed receivers had signed full contracts with the Vikings as undrafted free agents, while Thielen was only being paid for his time that day.
Nevertheless, he outperformed Nicholas Edwards, a tall receiver from Eastern Washington, in order to earn his contract with the Vikings.
Like it has been for all rookies, the transition to the NFL is tough.
"It's obviously different; it's faster and it comes at you a little faster. I'm trying to slow it down a little bit and come into my own here."
He clarified, "It can't get too complicated, it's just football."
"I've had help with all the rookie camps and OTAs, so I've had plenty of time to transition."
It's easy to be skeptical of the simple assessment. NFL football is well known for being more complex, esoteric and technical. The level of skill and football intelligence to perform at the NFL level is significantly different than in college, particularly in Division II. Thielen doesn't make much of the difference, and the scheme he ran was not too different.
"This playbook is pretty similar from my college playbook to here," he said when asked about the complexity of the NFL game. "Just a lot bigger, a lot broader. Not much more complex, just bigger."
It helps that the Vikings have a system friendly for wide receivers learning to play the game, without a lot of embedded option routes against defenses and more route packages designed to complement each other.
Fighting, presumably, for the fifth receiver spot, it's important that he not just flash the ability to learn and perform as an NFL receiver, however.
The former Maverick had very little experience with special teams in college or high school, and is learning much of what he needs to know on the fly. He relishes the challenge.
"I love it. It's a new aspect for me to learn and it's a lot of fun," he said of his relative inexperience playing on the kick units. He knows a lot of the techniques that make him an effective gunner, however, and he performed well during the drills.
He started off without much explosiveness or speed, but plus technique. Over the course of the drill, he improved, including a few plays where he demonstrated his lateral quickness, body control, flexibility and the capability to make cuts while still pushing forward.
Many of the strategies used to beat blockers on punts resemble the strategies used by receivers to beat press coverage, and that's what Thielen was drawing upon when he consistently used his shoulders to get skinny and dip underneath contact.
"Press coverage in college and here at the pro level just being a receiver, it's natural for me to get off the jams," he said of his adeptness against punt return blockers. "I really love that part, it's a lot of fun for me and I like doing it."
Thielen is well aware of how he is expected to make money his first year in the NFL, and is focusing on improving those special teams talents, but not to the detriment of the other tools he needs.
"I'm just focusing on getting better as a total football player," he said. "Special teams: that's a big spot for me to continue to improve. So I've got to improve there, and my wide receiver skills."
If he improves at the pace he showed today, we may be seeing him come September.