In football, momentum is the river one rides upon. Downstream is great. It is smooth sailing. When you start battling upstream current and reach a point that's dammed, diverted or divided, anything can happen.
Just ask Gary Patterson, whose TCU squad was enjoying a convincing victory over San Diego State until the tide turned and the Aztecs were a play or two at the end from pulling a major upset last Saturday.
Ask Oregon's football team, which has been fast-breaking past everyone until a Cal defense decided to throw down a nail board on the road Saturday.
Ask Kyle Whittingham, whose team raced to an 8-0 record and a Top-5 ranking and then watched his team struggle to score touchdowns in consecutive losses to TCU and Notre Dame.
Ask Bronco Mendenhall, whose 1-4 squad looked baked and done after leaving Logan on Oct. 1, but now has won four of five and has a chance at bowl eligibility and a No. 2 finish in the Mountain West Conference.
"As any athlete knows, momentum is the most unstoppable force in sports," according to PGA star Rocco Mediate, who took Tiger Woods to the wire in the 2009 U.S. Open at Torrey Pines. "The only way to stop it is if you get in your own way, start making stupid mistakes or stop believing in yourself."
Momentum changes happen all the time in games. They also happen during weeks of practice. Last Tuesday in Provo, the Cougars had three offensive linemen banged up, and center Terence Brown was carted off the practice field. It was a horrible practice.
Things changed Wednesday and Thursday, and on Saturday the Cougars won their first road game of the season, a 49-10 rout over Colorado State.
Wins can elevate and ignite momentum. Losing can contribute to more losing, or become a catalyst to making changes that lead to wins.
In the case of Utah, some simple miscues at the start of the TCU game threw up huge challenges for the confidence of the squad. Same in South Bend with that blocked punt for a TD.
Whittingham has to be examining every aspect of the past two games, but he's also hoping team leadership rises to the top to help. Mistakes, penalties and QB play have been a part of his squad's issues. Bad karma issues can domino on you for good or worse.
Will Whittingham make a change and start Terrance Cain at quarterback in place of Jordan Wynn? There are pluses and minuses to such a move. And it is heavily debated right now. Whittingham told reporters Monday he's sticking with Wynn, but added: "It's a competitive situation that is subject to performance and production. It's that way across the board."
Mendenhall had to fire his defensive coordinator to change momentum on his squad — and it worked. His rush defense went from 120th in the NCAA to 74th, but No. 1 in the last five games.
Sometimes you have to rattle the cage to kindle fire and change attitudes and break bad habits.
"The capture of momentum is the most significant job, and most normally that takes a significant event," said Mendenhall.
In BYU's case, Mendenhall said he doesn't want to take credit. But for his program, it meant rolling up his sleeves and being more involved and trying more to help the team than just be the head coach.
"It signified there would be change and made it visible in practice," he said. "The game was a byproduct of practice."
Mendenhall said he saw a change in the culture as players were challenged in everything from drills to meetings and then saw results in confidence and success.
"We're still gaining momentum. We can play better," he said. "I know our players and coaches feel that way, and it will be interesting to see what happens in the next two weeks remaining."
Work to turn BYU's situation around has been so intense, so focused on inner stuff, Mendenhall told reporters on Monday he had not even taken time to look at the league standings and didn't know that, if BYU won out, they'd finish second.
He continued: "I would say that would be nice if we earned it, but I'd rather see us reach our potential, and that will take a lot of work in two weeks to get us there."
Momentum, it is a very touchy thing.
It doesn't take much to bring it to a screeching halt, and it certainly doesn't take but a big play, personnel shake-up or a win to get it turned around.