Brandt called the story "something I have never witnessed" in his half-century in pro football.
"I think some teams will say it isn't worth the problem" to draft Te'o, said Brandt, who has the linebacker rated 19th overall in the first round.
The former Dallas Cowboys general manager added Thursday that Te'o's stock had plummeted after a poor performance in the BCS championship game.
"I don't think anybody considered him to be a top-five pick before all this happened," Brandt said. "In that game against Alabama, this was like a guy who was the best shooter in the world in basketball and here comes a game and he can't even hit the backboard. His play in that game was absolutely horrible. He missed on run blitzes; guys ran over him ..."
Te'o would hardly be the first player to see his draft stock sink because of off-field issues. Last year, North Alabama cornerback Janoris Jenkins fell to the second round after multiple run-ins with the law related to marijuana got him dismissed from Florida.
Warren Sapp in 1995 and Randy Moss in 1998 slid because of character concerns; both are now considered potential Hall of Famers.
Chicago Bears general manager Phil Emery said "it's no different what the red flags are."
"You've got to identify them," he said. "You've got to research it and then you decide what impact that has on the total person in terms of his ability to play football and to manage his life."
Oakland Raiders GM Reggie McKenzie agreed.
"It makes you go and get all the answers, cross your Ts and dot your Is and make sure," he said. "With any player, you have to make sure what you're getting from a character standpoint other than his ability, his talents. Try to get to know the guy. So, yes, it will weigh in heavily."
David Schwab, a senior executive at sports management firm Octagon, considered Te'o perhaps the most marketable player coming into this year's draft. As the face of a Notre Dame team that returned to national relevance, the Heisman Trophy runner-up had the name recognition of few college stars.
"Compassionate" and "heartwarming" were some of the adjectives Schwab would have used to describe his image.
Now, that persona will depend on the details that emerge about the story of a girlfriend who didn't exist.
"If he truly had nothing to do with it, I think the long-term damage is zero," said Schwab, who specializes in matching companies to celebrities.
In the short term, it's unlikely to see Te'o promoting any products, because a public appearance would turn into an impromptu news conference about the hoax. If uncertainty lingers about exactly what happened, Schwab said, many companies may hesitate to sign him.
But even if Te'o is implicated in the hoax, he could still eventually turn into a sponsor's dream if he blossoms as an NFL star.
"If you perform on the field, you quickly become marketable," Schwab said.
Look no further than Ray Lewis, the Baltimore Ravens linebacker who was charged with murder in 2000. The charges were dropped after Lewis agreed to testify against two other men and he subsequently pleaded guilty to a misdemeanor charge of obstruction of justice. This week he's a beloved figure heading into the AFC championship with retirement looming.
Teams may be less likely to take a risk on Te'o in the draft if they don't believe he can become a dominant player.
Brandt noted how the inside linebacker position doesn't carry as much importance in the NFL as it once did. In the last 10 years, only four inside linebackers were taken in the first round, although one of them was perennial All-Pro Patrick Willis of San Francisco.
"I think it would be different if it was a quarterback who would change the game," he said. "But linebackers are a piece to the puzzle; they don't solve the puzzle. Other than Ray Lewis, I don't know of any linebacker you say, 'We've got to have this guy.'
"[Inside] linebackers are not as important as they used to be. We're down to one or two first-round linebackers now."
Brandt wondered how Te'o could be so effective during the season, including seven interceptions "unheard of, like hitting .450 in baseball" and then so unproductive in the championship game.
"Between now and 97 days from now when the draft comes, there'll be a lot of people investigating just what took place," he said.