Get ready for the Baker Mayfield sweepstakes.

The Oklahoma Sooners' star QB was denied an extra year of eligibility by the Big 12 in a vote on a proposed new rule Wednesday, meaning this will be his last year in Stillwater. However, Mayfield is expected to graduate and would be eligible to join any school outside the conference as a graduate transfer in 2017.

"We're hoping we can make progress so we can get this changed before we get there," Oklahoma athletic director Joe Castiglione said.

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Mayfield was the Big 12 Offensive Player of the Year last season, passing for 3,700 yards and 36 touchdowns, finishing fourth in the Heisman voting.

Mayfield vowed "I will be making the most out of my last season I get to suit up for Oklahoma" in a long Twitter post to his fans.

pic.twitter.com/ulOYIcmO43

— Baker Mayfield (@baker_mayfield6) June 2, 2016

pic.twitter.com/ZeM3OZeysq

— Baker Mayfield (@baker_mayfield6) June 2, 2016

Big 12 faculty athletic representatives voted Wednesday on a rule that would have allowed non-scholarship athletes to transfer within the conference and not lose a year of eligibility, but they deadlocked 5-5.

Mayfield was a walk-on at Texas Tech before he left after his freshman season in 2013, then had to sit out to a season to satisfy NCAA transfer rules while also losing a season of eligibility in the Big 12.

Commissioner Bob Bowlsby said the Big 12 didn't want teams poaching their rivals' walk-ons by offering them scholarships.

Bowlsby: opposition to the walk-on rule change didn't want Big 12 teams luring other team's walk-ons with the promise of scholarships

— Jake Trotter (@Jake_Trotter) June 1, 2016

Missed this earlier. Baker Mayfield's roommate and #Sooners walk-on https://t.co/acLM3haqjW

— Ryan Aber (@ryaber) June 2, 2016

This rarely happens...this vote was about Baker Mayfield. 5 B12 coaches would rather face Kyler Murray in 2017 https://t.co/T66gSJqax2

— Bill Jones (@CBS11BillJones) June 2, 2016

Really hope some ADs are honest when asked why they voted against the rule and just say, "because Baker Mayfield is too good."

— Gabe Ikard (@GabeIkard) June 1, 2016

Rough day for Oklahoma: The Red River Rivalry goes to FS1, Baker Mayfield rule shot down, Texas smacks them down on expansion.

— Dan Wolken (@DanWolken) June 1, 2016

I'm starting to think Baker Mayfield will be OU's quarterback in 2017, as they join the SEC Conference.

— Carey Murdock (@CareyWWLS) June 1, 2016

Like the idea of Baker Mayfield cfb free agency. But if I'm him, I look at current crop of draftable QBs and start looking into draft suits.

— Adam Kramer (@KegsnEggs) June 1, 2016

Gonna be fascinating to see where Baker Mayfield ends up in 2017. He will be a hot commodity.

— Jake Trotter (@Jake_Trotter) June 1, 2016

So get ready for the Baker Mayfield sweepstakes, because that's a thing that will happen next January.

— Barrett Sallee (@BarrettSallee) June 1, 2016

In other topics discussed Wednesday: Bowlsby wants conference leaders to make decisions one way or the other on the lingering topics of expansion, a football championship game and a league network by the end of the summer.

Athletic directors spent about 90 minutes during the Big 12 spring meetings Wednesday in what were termed "philosophical discussions" about those issues that will ultimately be decided by the league's board of directors comprised of school presidents and chancellors.

The 10 directors, which include interim leaders at Baylor, Kansas State and Texas Tech, will join the conference meetings Thursday and Friday. They will have a significant amount of data to discuss this week and consider into the summer when returning to their campuses.

"Unless we find that there is something we just have missed ... I don't see any reason why we can't stay on that timeframe," Bowlsby said.

A research firm hired by the league has provided data that shows the conference would have a better chance to get into the College Football Playoff each season by expanding to 12 teams and playing eight conference games, along with a championship game. That is opposed to its current standing of 10 teams playing a round-robin conference schedule without a title game.

"There's an awful lot right about the way we conduct our competition. There's a lot right about playing a full round-robin in football and double-round in basketball. I think we're going to be a little bit slow to depart from that," Bowlsby said. "We don't want to give that away in any sort of way that doesn't provide at least equal or more rewards than what we currently have."

Castiglione described the round-robin schedule as a distinguishing characteristic for the Big 12, and pointed out that having a conference championship game wouldn't guarantee the winner going to the playoff like the Sooners did this season.

When asked about expansion, Texas athletic director Mike Perrin said he believes "the prudent thing" is for the conference to stay at 10 teams. He seemed a little more open to discuss the possibility of a championship game without expanding.

But the Longhorn Network remains a huge hurdle in any discussions about a league-wide network.

While some other schools have contacted the Big 12, Bowlsby said the league doesn't have what he would consider a list of expansion candidates and that such discussions "would be premature."

The Associated Press contributed to this report.