A number of top-tier players exit the Pac-12 following the 2017 college football season, leaving considerable voids to fill for the next campaign. From big bodies in the trenches, to explosive skill position players and some record-setters, the outgoing class features some impressive names.
The best players saying goodbye to the Pac-12 ranks are not all necessarily the most difficult to replace. For example, a pair of running backs who ranked among the nation's top ball carriers in 2017 — Ronald Jones II of USC and Oregon's Royce Freeman — left their respective program with names etched in the record books.
With Oregon retaining the explosive Tony Brooks-James, and USC's promising youngster Stephen Carr poised for the every-down role, neither Jones nor Freeman rank among the most difficult to replace. These are the players (in alphabetical order) with no evident heir on the depth chart, and a ton of production left to be replaced.
Tyrell Crosby, OL, Oregon
A driving force behind Oregon's No. 18-ranked scoring offense, Crosby dominated up front. He was a first team All Pac-12 honoree, and widely regarded as one of the premier linemen in the nation, carrying on the tradition of Ducks predecessors like Geoff Schwartz, Hroniss Grasu and Kyle Long.
Sam Darnold, QB, USC
When Darnold replaced Max Browne as starting quarterback in late September 2016, the entire trajectory of USC football changed. The Trojans went from 1-2, with the Clay Helton era appearing on the brink of an abortive conclusion, to winning a Rose Bowl and a Pac-12 championship.
Darnold's improvisational skills, which made him a coveted NFL prospect, opened up the USC offense in ways rarely before seen. His departure also makes 2018 the third offseason in the last five in which the Trojans have had a quarterback competition — fourth, if one counts 2014 when a new coaching regime and the ballyhooed Browne came on the scene.
Luke Falk, QB, Washington State
The resurgence of Washington State football is tied directly to the illustrious career of Falk (right). He took over as starting quarterback at the end of a disastrous 2014 campaign, but in his first full year as starter, the Cougars were in contention for a divisional championship. They again jockeyed for a North crown in 2016 and '17, while Falk piled up impressive numbers and became the conference's all-time leading passer.
Tragic circumstances lead to Washington State replacing Falk this offseason. Talented Tyler Hilinski, who started in an injured Falk's place in December's Holiday Bowl, died in January.
Uchenna Nwosu, LB, USC
Head coach Clay Helton lauded Nwosu as the "MVP of the defense" midway through USC's 2017 campaign, but even Helton could not know just how valuable the outside linebacker would be. His fourth-down stop on a Stanford goal-line rush in the Pac-12 Championship Game essentially sealed the Trojans' first conference title since 2008.
Nwosu's ability to defend the pass, blitz and stop the run with equal proficiency allowed defensive coordinator Clancy Pendergast freedom in other areas. That will be difficult to replicate next season.
Cody O'Connell, OL, Washington State
Washington State's prolific passing attack owed much to the outstanding play of its offensive line, anchored by O'Connell. Head coach Mike Leach praised O'Connell's improved technique throughout his tenure at Washington State, a difficult quality to recreate on its own.
Add the massive physical presence O'Connell brought to the Cougars front five at 6-foot-9, 350 pounds, and there aren't many offensive linemen anywhere at any level of football quite like him.
Isaiah Oliver, DB, Colorado
An exodus of standout talent departed the Colorado secondary following the Buffaloes' surprise run to the 2016 Pac-12 Championship Game. However, Oliver emerged to capably fill the void, intercepting two passes while breaking up another 13.
After losing Chidobe Awuzie and Ahkello Witherspoon the year before, Oliver's departure makes for another superstar defensive back the Buffs need to replace.
Dante Pettis, WR/Ret., Washington
Whether on offense or special teams, Pettis was an absolute game-changer for Washington football. The speedy Pettis had a knack for blowing past cornerbacks and getting deeper than the safeties on passing routes, and he applied the same combination of speed and evasiveness to run back a jaw-dropping four punts for touchdowns in 2017.
Pettis ran back nine punts in his career to set an NCAA record. It's unlikely his successor will match that number.
Harrison Phillips, DT, Stanford
Carrying on the tradition of outstanding defensive line play in 2017 was Phillips (right). While the Cardinal have effectively replaced other excellent players up front on the defensive side of the ball throughout head coach David Shaw's tenure, Phillips is a unique case.
He lined up on the interior at tackle, but made an impact more akin to a edge rusher. His versatility makes him one of the most difficult players to replace in all of college football.
Josh Rosen, QB, UCLA
UCLA may have fallen short of its team ambitions in 2017, but Rosen's return from a shoulder injury offered the most prolonged glimpse into the ballyhooed talent's ability yet. Rosen (above, right) was outstanding for the Bruins, leading the nation in passing yards for the first month of the regular season. His ability to fit throws into tight windows and unleash devastating long balls made him a thrill to watch.
Rosen's backup in 2017, Devin Modster, showed promise. His dual-threat ability and arm strength were both impressive, though in need of refinement. With a new coaching staff taking over, however, as well as the arrival of celebrated recruit Dorian Thompson-Robinson, the future of UCLA's quarterback job is very much up in the air ahead of 2018.
Vita Vea, DT, Washington
The 6-foot-5, 340-pound Vea was an absolute terror on the interior of Washington's outstanding defense. His strength and size made him virtually unblockable in one-on-one situations, opening up blitzing opportunities for Huskies ends and linebackers.