TCU used Michigan football's alleged sign-stealing against the Wolverines in last year's CFP semifinals upset, according to Yahoo Sports' Ross Dellenger.

The Horned Frogs won 51-45 in the 2022 Fiesta Bowl and advanced to the national championship in part because they mixed in "dummy signals" with real ones when calling plays, a TCU staff member told Dellenger.

"Sometimes we froze a play before the snap," a TCU coach told Dellenger. "We'd call a play and then we'd signal in another play with an old signal but we told players to run the original play."

Michigan and the Big Ten said last Thursday they had been informed of the NCAA's investigation regarding allegations the Wolverines sent representatives to opponents' games to learn play-calling signals, according to the Associated Press' Ralph D. Russo. The investigation dates back to at least 2021.

The investigation is not specifically about whether Michigan stole signs, which is not specifically prohibited by the NCAA, per Russo.

The probe instead involves what ESPN's Pete Thamel and Mark Schlabach described as an "illicit scouting ring." The NCAA bans "in-person scouting of future opponents (in the same season)," and Thamel and Schlabach reported Tuesday that Michigan analyst Connor Stalions bought tickets to watch games played by CFP contenders outside of the Big Ten over the last two seasons.

Stalions was suspended with pay on October 20 after ESPN initially identified him as a person of interest in the NCAA investigation.

One Big Ten coach told ESPN Michigan looked visibly "desperate" as it appeared to not know TCU's signals on December 31.

That source isn't the only coach who reportedly knew about the alleged scheme, which has become common knowledge among staff members of other Big Ten teams, according to Dellenger.

"We heard they had a guy pick plays pretty good and had all this information from not your typical ways of getting the signals," a Big Ten staff member told Dellenger. "We get into the game and it's the second quarter. I see him across the field and he's checking his 11x17 sheet."

Multiple opponents playing Michigan this fall have started using wristbands instead of signals, according to Dellenger.

The Wolverines hold an 8-0 record and could sit at the top of the CFP Playoff Rankings when they are released on October 31. ESPN reported Thursday it was unlikely the ongoing investigation would impact Michigan's ranking.