Every team that got a new head coach this offseason will be markedly different than it was the season prior. Even teams that merely changed coordinators or position coaches will have a slightly adjusted feel.
But some will be affected more than others, and some even more than that. A team that promoted from within, for example, stands to retain some core concepts from one regime to another, while a team that made an outside hire might experience wholesale changes.
Looking even deeper, a team like USC brought in Steve Sarkisian from Washington, but they didn't change coaching trees.
Sarkisian coached under Pete Carroll with former Trojans coach Lane Kiffin, and even though the two handle business very differently, the root of their schemes are closely related, like two divergent languages from the same family.
The following are programs that will feel the biggest change in their transition from one staff to another—all of which happened to change head coaches, though that wasn't necessarily used as a requirement.
But will that change be for better...or for worse?
Coaching Change: Charlie Strong to Bobby Petrino
Charlie Strong and Bobby Petrino are diametric opposites. This move is like going from the salad course to dessert without the transitional phase of the entree.
Strong is a no-nonsense boy scout who coaches tough, disciplined, win-ugly football. Petrino is a serial liar and ship-jumper who coaches up-tempo, vertical, win-by-outscoring-you football.
This might take some getting used to.
The biggest difference on this new staff will be risk quotient. Strong is one of the safest coaches a team could possibly employ, the same man today as he will be tomorrow as he was last Tuesday. Petrino is volatile and unpredictable; but when he's on, few coaches in America are capable of building a better program.
Combined with the infusion of Todd Grantham, who left the same position at Georgia to become Louisville's defensive coordinator, the Cardinals just added an offensive specialist and defensive specialist that have both proven capable of winning in the vaunted SEC. But both have also proven capable of failing there, albeit in different ways.
This could go in so many different directions, both good and bad, and it remains to be seen which one it will be. Either way, watching it all unfold will be appointment viewing.
Coaching Change: Bill O'Brien to James Franklin
I almost left this off the list.
Ideologically, I'm not sure there's much of a change from Bill O'Brien to James Franklin. Both are innovative offensive minds whom players love to play for. That won't change.
However, omitting this hire would have been a disservice to what Franklin brings to a football program—beyond what he does on the sidelines. Just as he did when he took the reins at Vanderbilt, Franklin has wasted no time in rousing the city, in suffusing Happy Valley with a belief that better days lie ahead.
There is also a lot of positional turnover. Defensive line coach Larry Johnson, the last holdover from the Joe Paterno era, is gone to Ohio State, while Franklin brought defensive coordinator Bob Shoop, a secondary specialist, over from Vanderbilt.
New offensive coordinator John Donovan runs an O'Brien-esque pro-style offense, and the schematic continuity on that side of the ball should aid Christian Hackenberg's development.
But this inclusion wasn't about schematics. There, Penn State will feel not-too-different in 2014 than it did the year prior.
This inclusion was all about attitude.
Coaching Change: Mack Brown to Charlie Strong
Charlie Strong's old program won't be the only one coping with a revised culture; his new one will need to take some time getting used to him.
Mack Brown ran the ship in Austin for the past 16 seasons, and he did so with a certain joie de vivre. He was a players' coach and a crowd-pleaser, and the ultimate, consummate Texan.
Strong offers a different culture. He's more severe and less playful, which might make him an awkward fit on the Longhorn Network but should definitely help him change the culture in the locker room—a locker room that has suddenly become accustomed to losing.
Strong's teams have never really lost consistently, and if those winning ways can translate to the Big 12, his program's TV network will forgive his made-for-radio charisma.
Coaching Change: Jim Grobe to Dave Clawson
Dave Clawson brings an adept offensive mind to Wake Forest, which is needed after the end of the prolonged Jim Grobe era.
Wake has finished last in the ACC in scoring offense each of the past two seasons, and it also finished 11th out of 12 in 2010.
Clawson is remembered for his one bad season running the offense at Tennessee, but he was always able to score points during his five-year tenure at Bowling Green, especially during a 10-3 conference championship campaign in 2013.
Clawson also brings his longtime coordinators, Mike Elko and Warren Ruggiero, over from the MAC, where they were the only staff to remain together for each of the past five years. Thus, even though the turnover from Grobe to Clawson will be significant, at least Clawson can maintain some continuity within his own system and principles.
"Your first spring is so important," Clawson told Heather Dinich of ESPN.com. "A lot of it is just establishing the culture of your program."
After five consecutive losing seasons, an established new culture is precisely what this program needs.
Coaching Change: Steve Sarkisian to Chris Petersen
Washington fell up when Pac-12 rival USC hired Steve Sarkisian away from Seattle, inking a contract with Boise State's Chris Petersen, who had long been coveted by bigger, stronger power-conference schools.
What Petersen and his staff, which he brought over largely intact from Boise, bring to this program is an ability to manage games—something Sarkisian could never quite learn to do.
The talent has been there for the Huskies these past few seasons, as Sark is one of the best recruiters on the Pacific coast. However, he and his staff could never get the team over the hump between the sidelines, leading to the backhanded moniker of "Seven-Win Steve."
Petersen brings a different attitude and track record, an ability to maximize the talent of his players once the whistle blows on Saturday afternoon. Unlike "Seven-Win Steve," his eight seasons at Boise State had an average win total of 11.5.
The old regime expected to bring in talent, develop talent, pull an upset or two, then play in the Las Vegas Bowl each season.
The new regime expects to win each time it takes the field.
Coaching Change: Dave Christensen to Craig Bohl
Dave Christensen is, always has been and probably always will be a good offensive coordinator.
That doesn't, however, make him a good head coach. He wasn't a bad head coach, per se, but he was always better suited leading an offense than building a program.
Craig Bohl is a program-builder. Plain and simple.
Say what you will about "playing at the FCS level," his three consecutive national championships since 2011 are a feat that every coach at every rank of football can and does respect.
Last year, en route to a 15-0 season, Bohl's North Dakota State Bison opened the year with a Week 1 win at Kansas State. The same Kansas State that routed Texas Tech in Lubbock and Michigan in the Buffalo Wild Wings Bowl.
NDSU was no joke.
Bohl now brings that philosophy to Wyoming, that specific, organized, confident bearing that it take to build a successful program. He won't just light up the scoreboard. He won't just tailor a defense. He won't spend exorbitant hours trying to sell his team to boosters.
All Bohl does is win football games. Winning sells itself.