The clear-cut stakes in Saturday's crosstown showdown have prompted the Southern California quarterback to look back a bit on his tumultuous career while the biggest game of all looms right in front of him.
''It's been a long ride for me, a very emotional, drama-filled ride,'' Kessler said. ''But I've always loved playing in front of the fans at the Coliseum. It's been a great journey for me to this game.''
Kessler has no idea what historians will make of his era in charge of the Trojans' offense. He doesn't even know how he'll remember the arc of a career that began under NCAA probation and has featured four head coaching changes, three winning seasons as the starter, several heartbreaking losses and a ridiculous array of off-the-field distractions.
The journey hits another landmark when the Trojans (7-4, 5-3 Pac-12) face No. 22 UCLA (8-3, 5-3) for the 85th time. The winner gets the Pac-12 South title and a berth in the conference championship game next week against No. 13 Stanford.
USC's three straight losses are its longest skid in the rivalry since 1998. They're a source of severe consternation among the fans who had to endure Kessler's UCLA counterpart, Brett Hundley, repeatedly declaring afterward that the Bruins ''run L.A.''
Kessler realizes a victory could change the perception of his entire career at USC, where he produced stellar numbers and led winning teams, but never carried the controversy-plagued Trojans back to college football's heights.
Kessler enters the showdown with 2,953 yards passing, 69.2 percent completion percentage and 25 touchdowns this season against just six interceptions. His sheer yardage is down from last season after Clay Helton elected to emphasize the run as interim coach, but Kessler's completion percentage and yards per pass are nearly identical to his first two seasons as a starter.
Facing a career-defining moment this weekend, Kessler is trying to remain the same steady, supportive leader who has carried the Trojans through dismal times.
''I really don't know what my (legacy) will be,'' Kessler said. ''Hopefully, people will look back and just realize all the stuff we went through, and that I always stayed consistent, always stayed positive and tried to keep us together over the years. I always seem to be so positive, but it was tough at times. It was very hard. I don't regret any second of it. Everything we went through, everything I've gone through, I've enjoyed it. I've enjoyed the ride.''
The Trojans are 4-2 under Helton, with their four-game winning streak ending last week at Oregon. USC is unranked for its crosstown rivalry game for the first time in Kessler's career and just the second time since 2001.
But Helton, Kessler and USC's leaders have restored stability and consistency to a program rocked by Steve Sarkisian's firing in October. They've kept the Trojans in the Pac-12 South race when they had every reason for their season to slide.
They also know they haven't won anything yet.
''We've got everything on the line this week,'' offensive lineman Zach Banner said. ''It's a rivalry, so it's always going to be a heated game. But if we beat them, we go. They beat us, they go.''
Kessler has learned about much more than football in his near half-decade on the USC campus, and he's still processing every lesson. He has been the players' spokesman during the toughest weeks and a team leader at all times, smoothly succeeding Matt Barkley in the role.
Yet Kessler wants a memorable season-ending performance against UCLA before he heads off to a bowl game and the NFL. He passed for just 214 yards against the Bruins last season, and he managed only 174 yards two years ago in his first appearance against the Trojans' biggest rivals.
''Finishing the season out the right way is something that's very important,'' Kessler said. ''It's something that you're going to be remembered for. We have a chance to do something great this year still, even after everything that's gone on. So this week is very important, but even the weeks after that will be important for us to leave a legacy.''