This is the same Oklahoma team. The same Sooners that this time last year were on the verge of disaster.

That couldn’t win a big game anymore under coach Bob Stoops. That no longer ruled the Big 12. That was set up for a spectacular fall after an embarrassing 34-point loss in a bowl game to a team playing a backup quarterback.

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Then Baker Mayfield got eligible, Stoops hired a new offensive coordinator (Lincoln Riley) and OU is now the hottest team in the game heading into the College Football Playoff.

The reason is simple: the play of Mayfield, the Sporting News 2015 Player of the Year.

“I don’t think you can overstate how important Baker has been to this team,” Stoops said.

Maybe even the difference between playing for it all and playing out the string – both the season and a spectacular coaching career in Norman for Stoops. Fair or not, Stoops was feeling heat heading into this season, and had made changes to the staff in the offseason to address some glaring problems.

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At the top of the list was the quarterback spot, where OU had struggled the previous two seasons and where the Sooners hadn’t had a game-changer in the most important position on the field since Sam Bradford won the Heisman Trophy in 2008. Mayfield transferred from Texas Tech last season, and despite OU’s significant efforts with the NCAA, he wasn’t granted an appeal to play immediately.

On the outside looking in, OU’s desperation to get Mayfield eligible seemed strange, especially considering the Sooners were coming off a big win over Alabama in the Sugar Bowl – a game where quarterback Trevor Knight played well and gave a hint of big things to come in 2014.

Now we know why OU was so intent on getting Mayfield eligible in 2014: he’s a game-changer. He’s a program-defining player whose spirit, intensity and moxie rub off on others around him, forcing them to perform at his level.

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“I never had an idea of changing the way we do things around here,” Mayfield said. “I just wanted to fit in and do whatever I could to help.”

All he did was make OU a national power again, and lead the Sooners to the College Football Playoff – something that seemed like a pipedream this time last season. Mayfield threw for 35 touchdowns, and rushed for seven more, had 3,383 yards passing and completed nearly 70 percent of his throws.

Last season, with essentially the same two-deep depth chart, Oklahoma’s quarterbacks threw for 17 TDS and 17 INTs and the Sooners lost five games. But the impact of Mayfield goes far beyond numbers.

His magnetic personality and carefree style helped loosen up a team that at times played much too tight over the last two seasons. OU played tight, made mistakes, lost games and lost its mojo.

Mayfield brought it all back, from the way he immediately connected with teammates when he first arrived last season, to how he handled his responsibility after winning the starting job in fall camp – to how he played week after week.

“Football should be fun,” Mayfield said. “We’re playing a game. We can be serious and we can be focused on what we have to do every single play. But the bottom line is we’re having fun playing a game.”

No one played it better in 2015.