Two years later, Plank wants to set the record straight.
"These decisions were beyond me, and I think there is this perception that maybe I have greater sway than I do," said Plank, a former Maryland special teams football player and member of the board of trustees.
In an interview, the 42-year-old billionaire entrepreneur acknowledged that he contributes plenty of ideas and money, but said he does not issue mandates about such things as conference shifts or coaching changes.
"I'm a supporter and endorser, just like anyone else," he said.
Plank adores watching the Terps athletic teams, whose uniforms his company designs. He timed his return from a Paris business trip so he could attend the home football game against Ohio State on Oct. 4. Under Armour's Tide Point headquarters is filled with posters of Terps athletes in action, and the colorful design of its harborside, synthetic-turf field evokes Maryland's own.
Plank has often provided a plane for the Maryland athletic department's use. According to university documents, he paid for $31,735 in charter flights when the school conducted the search that led to football coach Randy Edsall's 2011 hiring.
On Friday, Maryland announced that Plank had committed $25 million toward a plan to transform Cole Field House into a $155 million indoor football practice facility and academic research complex.
Plank is involved in the Cole project conceptually as well as financially. He and other school representatives toured Oklahoma State University's football facilities a few years ago to see if the design could have applications for Maryland.
He is passionate about the creation within Cole of an "innovations" center to expose students to entrepreneurship.
"The last thing I want to be is the booster guy who is perceived as trying to woo an athlete because I think he can play well for us for the next three or four years," Plank said. "I think our commitment needs to be much greater than that."
But, no, he said: He doesn't set athletic department policy.
After former Maryland football coach Ralph Friedgen suffered through a 2-10 season in 2009, fans speculated on message boards that Plank might buy out the final two seasons of Friedgen's contract. Plank said he never considered it. For one thing, he and Friedgen were friends. For another, Plank said, it would not have been his role.
"I support our coaches, bar none," Plank said. "I don't make decisions on whether they stay or whether they go."
After Maryland announced it was leaving the Atlantic Coast Conference in November 2012, Plank was confronted directly with the perception that he was behind the Big Ten move.
"I heard it from a prominent former executive from Maryland — that was their assumption," Plank said. "And I'm sitting here looking and going, 'I've got a $3 billion day job as a public company's CEO.' I'm incredibly supportive and respectful of our Board of Regents and our administration. But are you kidding me?"
Following the Big Ten move, Forbes.com speculated whether Plank would become one of a "growing class of billionaires funneling tens of millions of dollars into college athletics. From Phil Knight at Oregon, to T. Boone Pickens at Oklahoma State, to Terrence Pegula at Penn State, some of the richest alumni in America have decided to personally fund large chunks of their alma mater's sports programs."
Knight, the chairman of Nike, and Plank fall into a special category, said Paul Swangard, managing director of the University of Oregon's Warsaw Sports Marketing Center.
"I would describe Knight and Plank as financial supporters who can give more than money," Swangard said. "They are the kind of backer who can bring a lot more than just a financial boost. They are bringing their own brand with them, and that makes them unique. You hear it all the time — if you're with Nike, you're a Duck fan. I assume it's the same with Under Armour and Maryland, and there's nothing wrong with that."
Swangard said it's common for observers to pose a question for which there is no easy answer: "At what level does that philanthropy translate into influence?"
Major-university athletic departments often need big donors to keep pace with their peers.
"The game has become, 'Find those sources of revenue, try to have as few strings attached as possible, and take the money,'" said R. Scott Kretchmar, a Penn State professor of exercise and sports science who formerly served as the school's faculty athletic representative.
Plank resists the designation of uber-booster.
It's partly, he said, because other Maryland alumni — and the school itself — need to pitch in more money themselves.
"You came to Maryland, take some pride in our state," Plank said. "It shouldn't just be, 'Don't worry, I'll do it.' I'm not. Because we're all in this thing together."
The Cole development, which still requires final approval of the Board of Regents, would be funded with $25 million in state funds and $25 million from the university, to be repaid from Big Ten Conference revenues. Most of the remaining $105 million would come from private donations, including Plank's $25 million and $20 million more already committed by others.
One metric used to measure support is the alumni participation rate, said university spokesman Brian Ullmann. Based on the number of graduates who donate to the university divided by the total number of living alums, Maryland's participation rate is around 9 percent.
The rate at other Big Ten schools is higher — as much as 19 percent at Michigan and 14 percent at Ohio State, Ullmann said.
"We don't get that we're the state school," said Barry DesRoches, a longtime Maryland booster and donor. "That doesn't seem to exist to the degree that it exists at an Ohio State or Penn State or Wisconsin and other Big Ten schools. I hope we can embrace the concept of what a state school is in the Big Ten."
With the aid of Cole's planned new center for budding entrepreneurs, Plank said the school has an opportunity to market itself to athletes and other students as "the entrepreneurship university."
University President Wallace D. Loh said Plank told him the school could distinguish itself.
"He told me, 'Look, I'm not just interested in an indoor facility, although we absolutely need this to be highly competitive in the Big Ten,'" Loh said. "He said that every Big Ten institution has an indoor facility, so nobody is going to pay attention if we have an indoor facility. What makes us special — unique in the nation — is that we're combining this facility together with the academic mission of the university. I want all 38,000 students to be exposed to innovation and entrepreneurship."
Loh also said Plank "was the first person to say, 'I want to keep the Cole name.' This is called branding."
Alumni have a fond association with 59-year-old Cole, which was the home of Maryland's men's and women's basketball teams and the site of the 1966 NCAA game in which Texas Western became the first team to win the championship with a starting lineup of all African-American players.
Plank said he regards Maryland as "family," which means supporting it in difficult decisions such as leaving the Atlantic Coast Conference after 61 years. Maryland will make about $98 million more during its first six years in the Big Ten than if it had remained in the ACC, according to internal emails obtained last year under a public records request.
"Nobody likes change, especially not change for change sake. But I think there were probably other mitigating factors, including economics, that played a large role in this," Plank said. "You can't ignore that and, frankly, Maryland is a school that needs other economic sources, because boosters and fundraising has not been our strength."