There are reasons for Bay Area football fans to watch the Sun Bowl even though Stanford star Christian McCaffrey isn’t playing.

Atop the list is the player atop the lists: North Carolina junior Mitch Trubisky, projected to be the No. 1 quarterback picked in the upcoming NFL draft, could be starting for the 49ers next season.

“I don’t believe there’s a first-round quarterback outside of Trubisky,’’ ESPN analyst Mel Kiper said. “Teams reach for quarterbacks, overdraft quarterbacks, all the time.”

Several steps separate Trubisky, who reportedly received a first-round grade from the NFL’s Draft Advisory Board, from becoming the franchise quarterback at Levi’s Stadium.

*** He must leave school, and that’s not a given. Trubisky plans to delay the decision until after the Sun Bowl on Friday. (The deadline for early-entry players to declare for the draft is Jan. 16.)

*** The 49ers must be in position to select Trubisky. They’re currently slotted for the No. 2 pick, with quarterback-needy Cleveland holding the top spot.

*** Management must determine Trubisky is worth the investment.

“For all of Trubisky’s talent,’’ CBSSports.com draft analyst Rob Rang noted in an email, “the fact that he was unable to earn a starting role until this, his third full season with the Tar Heels, is a bit disconcerting.’’

Trubisky’s climb up the draft boards has been as swift as that of any quarterback in recent years.

Raised in Mentor, Ohio, he was a coveted but less-than-marquee prospect who earned three stars from major recruiting services.

He sat out his first season at North Carolina, then was a backup for two years before taking over the starting job for the 2016 season.

Trubisky’s 12 starts to date constitute the entirety of his relevant college career. But he made the most of it, completing 68.9 percent of his passes, with 28 touchdowns and only four interceptions

Quarterback is the toughest position to evaluate, by far. Trubisky’s limited experience makes the process more complicated by an order of magnitude.

“We’ve had quarterbacks with fewer starts that didn’t go in the first round,’’ Kiper said. “But for a first-round quarterback, maybe a top-10 pick and maybe a No. 1 pick overall, (it) has to be a little bit bothersome.”

Adding to the dilemma: Only a handful of Trubisky’s starts will have come against defenses with enough future pros to provide a sound basis for evaluation.

He shredded Florida State and Miami and was brilliant against Pittsburgh, whose coach, Pat Narduzzi, is one of the sharpest defensive minds in college football.

An efficient performance against Stanford could frame the top of the draft.

You can see him going in the first round,” said Cardinal defensive coordinator Lance Anderson, who has studied all of Trubisky’s starts.

“You watch him and see that he’s improved as the year has gone on. You see him make better decisions. He has good footwork, he can keep the ball in the zone read, he’s accurate, and he can make all the throws. He’s got a lot of tools.”

Trubisky’s lack of meaningful experience would be a red flag if not for those tantalizing tools, which fit the model for quarterbacks selected No. 1 overall.

There’s also the small matter of supply and demand. More teams at the top of the draft need quarterbacks than there are quarterbacks worthy of being taken at the top of the draft.

Trubisky is viewed as the best of a mediocre group that includes Notre Dame’s DeShone Kizer and Clemson’s Deshaun Watson.

“Let’s get this out of the way,’’ ESPN’s Todd McShay wrote in his latest mock draft. “No QB in this class is worth the No. 1 pick.’’

Rang’s assessment of Trubisky was a tad more nuanced.

“He’s not as safe a prospect as any of the four quarterbacks taken with the No. 1 or No. 2 overall picks in the past two drafts,’’ Rang said, referring to Jameis Winston, Marcus Mariota, Jared Goff and Carson Wentz.

“But need at the position could earn him this high of a selection anyway.”