It certainly isn't a struggle to find five Bruins to know, so here goes nothing.
Josh Rosen, QB, #3
Rosen, a true freshman, was the top-rated quarterback recruit in his class. He had a dazzling debut against Virginia in UCLA's season opener as he posted an 80% completion percentage while throwing for 351 yards and three touchdowns. Some said it was the best performance by a true freshman QB since 2000. However, like all freshmen, Rosen has his fair share of struggles since. In his second start against UNLV, he went 22-42 for 223 yards with a touchdown and an interception. It was the first road start of his career, so him not putting up the same type of numbers as he did against Virginia is understandable.
However, his third start has to be somewhat concerning for UCLA. Against BYU, Rosen struggled mightily. He completed just 11 of his 23 pass attempts for 106 yards a touchdown, and three picks. The Bruins were able to escape with the win, but the Cougars' defense is similar to what Rosen will see week in and week out in the Pac-12.
So, really, it's hard to know what to expect from Rosen against Arizona. There's no doubt that he's as talented as any QB in the country. He could very well throw for 300 yards and three touchdowns again. Arizona has been bit by big plays this year from teams that are certainly less talented than UCLA. But on the other hand, this will be Rosen's first conference road game, and so it would be unsurprising if he had a game similar to the one he had against BYU.
Paul Perkins, RB, #24
While UCLA's passing game has been inconsistent this season, UCLA's ground game, led by Paul Perkins, has been anything but. When Josh Rosen struggled against BYU, Perkins picked up the slack and ran for 219 yards. He's currently averaging 143 yards per game this season on 7.4 yards per carry. You could make an argument that he's the best running back in the country.
Other than a few series here and there, Arizona's run defense without Scooby Wright III has actually been pretty solid. Obviously Perkins and UCLA's offensive line will be far and away better than anything UTSA, Nevada, and NAU had though. If Arizona can slow down UCLA's running game and force Rosen to beat them through the air, I'd really like their chances to pull off the upset. Arizona did hold Perkins to just 78 yards on 21 carries in last year's matchup.
Ishmael Adams, CB, #1
The Bruins lost starting senior cornerback Fabian Moreau for the season after he suffered a lisfranc injury, but they will get Ishmael Adams back. Adams was suspended for stealing an Uber driver's cell phone, but has been reinstated just in time for Saturday's game. It's a big addition for the Bruins. Adams started in all 13 games for UCLA last season, and had two interceptions -- both of which he returned for a touchdown. He's also a vital special teams player as he returned 21 punts and 26 kickoffs last season for an average of 9.2 and 22.7 yards, respectively. He returned one kickoff for a 100-yard touchdown too.
In 2013, Adams had four interceptions and was seventh on the team in tackles.
Bottom line, Adams is a guy that is capable of making game-changing plays.
Jordan Payton, WR, #9
Payton led the Bruins in receiving last season with 954 yards, and he's quickly become Josh Rosen's favorite target. In three games, Payton has 183 receiving yards and two touchdowns. In last season's matchup, Payton shredded the Arizona defense with six catches for 119 yards and a touchdown.
Arizona has allowed a receiver/tight end to get over the 100-yard mark in two of three games this year, and Payton is an obvious candidate to be the third player to do it.
Isaako Savaiinaea, LB, #44
Myles Jack is out for the season, and one guy that will have to step up in his absence is junior LB Isaako Savaiinaea. Savaiinaea did not play much in his first two years at UCLA, but this season he has carved out a role for himself in the defense. Against BYU, Isaako had a team-high 14 tackles, including 1.5 sacks. That standout performance helped him take the team lead for tackles this season with 19. He's also just one of four Bruins to have a sack this year.
Savaiinaea is no Myles Jack, but he has proved that he can be an effective player in his own right.