Josh Rosen and Sam Darnold are valued draft prospects for many excellent reasons. They're also not perfect.

And the football world saw both aspects from each quarterback Saturday night in what was likely the final occasion they'll square off in college.

Rosen was lethal in rhythm, showcasing a blend of elite passing skills and helping UCLA stick with its pre-eminent rival into the fourth quarter at the Los Angeles Coliseum. But he threw a costly interception in the end zone. Darnold displayed his playmaking ability and guided the Trojans to a 28-23 triumph. But a lingering problem led to a turnover.

Their performances offered evidence that fits whichever narrative a viewer prefers—and perhaps is waiting to see.

Early on, Rosen picked apart the USC defense. Drops, penalties and a missed field goal stopped the Bruins from putting up more points than the seven they managed in the first half, but the junior consistently showed off his velocity, accuracy and touch. He rarely made a bad throw in the first two quarters.

He lofted two perfect downfield passes to Jordan Lasley before the break, although an unrelated penalty negated one of them, which would've been a 53-yard gain. This 41-yard connection, which Waiting For Next Year's Jake Burns relayed, found its way into the box score with 8:17 to go in the first quarter:

Rosen threaded a third-down conversion to hit Austin Roberts and beat man coverage, then whipped an 11-yard touchdown to Lasley on the following snap to help even the score at 7-7 with 6:48 to play in the first. Later in the opening half, he patiently waited for Lasley to find space while he dealt with an unblocked rusher on a fourth down.

Those three plays defined Rosen's confidence, but he often recognized when to take the safe option.

Rosen found Theo Howard, who was sitting in a soft spot of USC's zone. He went through a progression and wisely decided on a checkdown to Bolu Olorunfunmi, who picked up seven yards. Rosen let the playmakers do the heavy lifting.

From his footwork to his arm talent to his typically smart decisions, it was once again clear why he's a heralded passer. However, "Bad Rosen" appeared at an untimely moment, and one ugly choice reversed a game full of smart decisions.

Trailing 14-7 in the third quarter, UCLA had reached the red zone. After trying to look off USC safety Marvell Tell III, Rosen stared down Roberts and waited far too long before firing the pass. Tell had plenty of time to jump the seam route and snatch the interception, as ESPN Radio's Steve Mason relayed:

Along with "don't throw late over the middle," "don't throw late in the red zone" is a commandment for quarterbacks. Rosen has fallen short of unequivocally obeying those rules this season, and those mistakes proved critical in losses to Memphis and USC.

Rosen added a lovely 27-yard touchdown to Lasley in the fourth quarter, finishing the clash 35-of-52 with 421 yards and three scores. From an individual perspective, he outplayed Darnold. But his counterpart celebrated a win after posting a 17-of-28 line for 264 yards.

USC's signal-caller impressed as an improviser and mobile threat. Darnold gave the Trojans a 14-point lead in the third quarter thanks to his seventh career rushing touchdown, and he spent much of the night maneuvering in the pocket and extending plays.

His entire skill set appeared on a 25-yard completion late in the second quarter. Darnold stepped up to avoid a rusher, rolled slightly to his right and snapped a gorgeous ball to Deontay Burnett on the sideline. SI Now's Max Meyer relayed the action:

Mobility? Check. Velocity? You bet. Placement? Nailed it. There aren't many college quarterbacks who can execute that sequence.

But Darnold wasn't always so calm.

Heading into the season, inconsistent footwork and jumpiness in the pocket stood out as key areas he needed to address. That combination flared Saturday, resulting in an overthrown pass and an easy interception for Jaleel Wadood.

And while you can respect Darnold's competitiveness, he needed to show better situational awareness. With halftime approaching, he escaped pressure and scrambled toward the goal line, but UCLA tackled Darnold short of the first-down marker. The Trojans didn't have a timeout, so the drive ended inside the 5-yard line.

ESPN.com's Arash Markazi noted the redshirt sophomore's duality:

His mistakes ultimately didn't matter Saturday, but his margin for error will be substantially thinner in the NFL.

Soon, Darnold and Rosen will decide whether to forgo their remaining eligibility and pursue that professional dream. There's no doubt NFL clubs are closely monitoring the Los Angeles duo. According to Joey Kaufman of the Orange County Register, scouts from 20 teams were in attendance Saturday.

Whichever franchises eventually select the quarterbacks will tout their strengths, and both players have top-tier skills. But those two NFL teams will also be quietly prepared to address the issues that continue to show up.

While the good moments make Rosen and Darnold worth a high draft selection, that doesn't mean the bad and ugly can be ignored.

Stats from cfbstats.com or B/R research. Quotes obtained firsthand unless otherwise noted. Follow Bleacher Report CFB Writer David Kenyon on Twitter @Kenyon19_BR.