Change is constant in college football. 

Offenses evolve and defenses change to try to keep up with them. Coaches move from school to school, and every year, players graduate or leave early for the NFL. They’re replaced each season by a new set of freshmen straight out of high school. Some of these newcomers become superstars who will one day need to be replaced by new freshmen.

The 2017 season won’t be any different. There are plenty of great players who have moved on and are currently preparing for this spring’s NFL Draft. Meanwhile, at campuses all across the country, as spring practice gets under way, there are new faces looking to fill the large shoes they left behind.

Let’s take a look at the 10 biggest pairs of shoes waiting to be filled, and the players looking to fill them.

Deshaun Watson, QB, Clemson

There’s no denying the amazing improvements made at Clemson ever since Dabo Swinney took over the program. All the hard work culminated in a national title last season, as Deshaun Watson led the Tigers past Alabama. But 2017 will be interesting because we’ll find out just how transcendent Deshaun Watson was as a talent.

Of all the players in the country, Watson could be the most difficult to replace, not just because he was an amazing player for Clemson but because of expectations following a national title. There are a lot of people around Clemson who are looking at Hunter Johnson as Clemson’s QB of the future. Johnson is a five-star member prospect ranked as the No. 2 quarterback in the 2017 class.

But while Johnson may be the quarterback of the future, that might not mean he needs to be their quarterback of right now. I’m not sure Swinney will want to hand the keys to this national championship car to a freshman, particularly when he has veteran options like Kelly Bryant, Chase Brice and even Zerrick Cooper around.

It will be interesting to see how those three perform this spring, as one of them is likely to be Watson’s replacement.

Dalvin Cook, RB, Florida State

While Leonard Fournette has a lot more draft hype surrounding him at the moment, we already know how LSU will replace him ... the same way it did last season: Derrius Guice. The situation at Florida State isn’t as clear. 

Cook leaves Tallahassee, Florida, as the Seminoles’ all-time rushing leader, and he did that in only three seasons. While he was the clear-cut choice to replace Devonta Freeman a few years ago, the choice isn’t as obvious this time around. Jacques Patrick has served as Cook’s backup but didn’t see much playing time last season. He definitely has the size to be an every-down back but lacks the top-end speed that Cook had.

Of course, in Patrick’s defense, not many players have that speed.

Fisher has said that Florida State may go with a running back by committee approach in 2017, but the one name to keep an eye on this spring is Cam Akers. The No. 1 running back in the 2017 recruiting class, the five-star enrolled at Florida State in January, meaning he’s available to practice with the team this spring.

While Fisher may start the spring thinking he’s going to go with a committee, Akers has the kind of talent to change his mind.

Christian McCaffrey, RB, Stanford

McCaffrey may not have had the same kind of season in 2016 that he did in 2015, but the fact remains that when it comes to the Stanford offense, he was the show. It seemed like everything Stanford did with the ball revolved around McCaffrey, and now the Cardinal need to replace him.

Fortunately, we all got an idea of how Stanford plans to do that in the team’s bowl game. 

With McCaffrey sitting the game out to get ready for the NFL Draft, Bryce Love stepped into his spot against North Carolina in the Sun Bowl and rushed for 119 yards on 21 carries. Earlier in the season, with McCaffrey out with an injury, Love started against Notre Dame and rushed for 129 yards on 23 carries. 

While he may not have the same kind of versatility as McCaffrey, Love can scoot and will give Stanford a breakaway threat. The concern will be whether or not Love can stand up to a full season of being The Guy, as he’s listed at 5-foot-10 and 187 pounds.

Alabama’s front seven

All right, so this isn’t one particular player. To be fair, while working together, Jonathan Allen, Reuben Foster, Tim Williams and Ryan Anderson felt like some kind of hybrid juggernaut. Alabama defenses are always Alabama defenses, but these four played a huge role in the 2016 defense causing so many turnovers and converting a healthy portion of them into defensive touchdowns.

Odds are very much against the 2017 Alabama defense being the touchdown-scoring force it was in 2016.

It will still be pretty damn good, though, because behind the monsters that are leaving await new ones -- monsters with names like Da’Shawn Hand. Hand was one of the top recruits in the country a couple of years ago, but he just hasn’t received as many snaps at Alabama as he might have elsewhere because there’s always so much talent already on the roster. This season will be Hand’s chance to shine on a full-time basis, and he has the ability to be the next top-five pick to come from Tuscaloosa.

He’ll be joined by Da’Ron Payne, Shaun Dion Hamilton, and Anfernee Jennings.

Mitch Trubisky, QB, North Carolina

While there’s a lot of debate about what Trubisky will be on the NFL level considering his short college career, there’s little doubt that he had a fantastic season for the Tar Heels in 2016 and will be difficult to replace. 

There are a lot of names in play to win the starting job, and the battle definitely begins this spring. Some consider Chazz Surratt the favorite to win the job. He redshirted the 2016 season and was a four-star member of North Carolina’s 2016 class. He does have competition in Nathan Elliott and Logan Byrd, both of whom have a shot at the job.

And while they may not be there this spring, there are wild card contenders to consider. Former LSU quarterback Brandon Harris and former Notre Dame quarterback Malik Zaire are on the transfer market right now, and both have been connected to North Carolina at some point since announcing their decisions to transfer.  

Ohio State’s secondary

When the NFL Draft begins, there’s a very good chance that Ohio State could yet again have two top 10 picks in the first round. Both of whom could come from its secondary, as many mock drafts across these here interwebs have Marshon Lattimore and Malik Hooker being selected early.

Which is good news for Ohio State recruiting, but bad news for Ohio State’s secondary, which has to actually replace them both this year. The good news for Ohio State is that it recruits at a level few other schools can, and there’s rarely a shortage of talent available.

If early spring practices are an indication, Damon Webb and Erick Smith have the inside track on the starting safety positions, while Denzel Ward and Damon Arnette can say the same at cornerback. That being said, a lot can happen between March and September.

Jabrill Peppers, LB/S/Returner/Doctor/WR/QB/Chef, Michigan

Honestly, I don’t know that Peppers was the best player on Michigan’s defense last season. Jourdan Lewis was fantastic at corner yet again, while Taco Charlton took a major step forward to become a disruptive force on the defensive line. Still, even if you can argue Peppers wasn’t the best player, he’s going to be the hardest to replace simply because he could do so many different things for the Wolverines.

Michigan defensive coordinator Don Brown once described all the things Peppers was asked to do in Michigan’s defense as “criminal” because it just seemed like too much, yet Peppers did it.

While they won’t be Peppers, guys like Noah Furbush, Josh Metellus (who replaced Peppers in the Orange Bowl) and Jordan Glasgow could all be used at linebacker or the “Viper” position that Peppers played. Because when it comes to replacing a guy who did as much as Peppers, you’re going to need more than one player. 

And that doesn’t even include what Peppers did on special teams.

Washington’s secondary

There were plenty of skeptics about Washington last year. Before the season began, I could definitely have been considered one of them. Once the season began, however, I quickly jumped on board because when I saw that Huskies defense get to work, I knew it was going to be a real problem in the Pac-12.

The key to the Washington defense, in my mind anyway, was its secondary. It was fantastic, and when you have a secondary you can trust like you could with the Huskies, it frees you up to do so many different things with your front seven. 

Even though Washington lost the game, just ask Lane Kiffin or Nick Saban how much fun they had facing that Washington defense in the College Football Playoff Semifinal last year.

Unfortunately for Chris Petersen and his team heading into 2017, a major portion of that secondary is gone. Budda Baker, Kevin King, and Sidney Jones are off to the NFL and will be extremely difficult to replace. While I have no doubt that Washington will still have a sturdy defense in 2017, there’s no way its secondary will be as strong, even with newcomers like Taylor Rapp around.

It will be very interesting to see how Washington goes about replacing those three, and it starts this spring.

DeShone Kizer, QB, Notre Dame

Notre Dame is coming off a horrific season, and while Kizer recently took the blame for it as he prepped for the NFL Combine, the truth is it wasn’t his fault. While he had bad moments, Kizer and the Notre Dame offense still scored 31 points per game. The 28 points per game the defense allowed weren’t on Kizer.

In fact, without Kizer at quarterback, Notre Dame may not even have finished 4-8.

Now coach Brian Kelly must head into 2017 not only on the hot seat but working in a new quarterback. The clear favorite to be that quarterback is Brandon Wimbush, who was one of the top quarterbacks in the 2015 recruiting class but hasn’t seen much time on the field with the Irish. In fact, he’s only thrown five passes in his college career, and they all came in 2015.

Wimbush won’t just be handed the gig, though, as sophomore Ian Book will receive plenty of reps this spring as well.

Oklahoma’s two-headed monster at RB

Last winter, it was Oklahoma quarterback Baker Mayfield and wide receiver Dede Westbrook in New York as finalists for the Heisman Trophy. While both had spectacular seasons, it would not be hard to make a case that neither of them would have been there without either of Joe Mixon or Samaje Perine

That two-headed backfield monster combined to rush for 2,334 yards and 22 touchdowns. They also helped as receivers out of the backfield -- though that was mostly Mixon -- as they caught 47 passes for 644 yards and six more touchdowns. 

Now both are gone, as is Westbrook. While Westbrook had a terrific season, I don’t think Oklahoma will have nearly as much trouble replacing his production as it will the numbers of Mixon and Perine. So where will the Sooners turn?

I don’t know!

The leading returning rusher is Abdul Adams, but he only carried the ball 53 times for 283 yards and no touchdowns last season. 

The interesting name to keep an eye on this spring will be Rodney Anderson, who came to Oklahoma as a four-star recruit in 2015 but suffered a season-ending injury during Oklahoma’s second game of the 2015 season. He then missed all of 2016 after he suffered a neck injury during a scrimmage before the season began.

If he can stay healthy this spring, Anderson could take over the starting spot before fall arrives.