The 49ers have been transparent in their study of five quarterbacks who are generally regarded at the top of this year’s draft class.

The team has acknowledged meeting and attended workouts of Mitchell Trubisky, Deshaun Watson, DeShone Kizer, Patrick Mahomes and Davis Webb.

The 49ers are fully expected to draft a quarterback next week. But that list is not limited to just the five quarterbacks who are expected to be chosen within the first two rounds.

But there are certainly more than just those five options for the 49ers. In explaining recently why the 49ers have shown no interest in re-signing Colin Kaepernick, coach Kyle Shanahan explained he prefers quarterbacks of similar styles who fit his offensive system.

“If you have your pick of the best world, you’d like those guys to be somewhat similar,” Shanahan said, “not just because that’s how you want the quarterbacks, just because of the work you’re doing for the rest of the guys on the roster.”

The best fit for Shanahan’s offense after the projected first wave of quarterbacks is Pittsburgh’s Nathan Peterman, according to one draft expert. The 49ers have kept their interest in Peterman lowkey. The club conducted a formal interview with Peterman at the NFL scouting combine, a source told NBC Sports Bay Area.

“He can run play-action. He’s played under center. He looks like an NFL quarterback,” NFL analyst and senior producer of NFL Films Greg Cosell said of Peterman. “Some people are going to say that his arm is not strong enough, and that’s valid. It may not be. That’s a decision everybody will make on their own. Some guys might say it’s strong enough. Others might say it’s below the level at which you can be a quality starter. That’ll be in the eye of the beholder.”

Peterman (6 foot 2 ½, 226 pounds) started his final two seasons at Pittsburgh after transferring from Tennessee. During his final two college seasons while running a pro-style offense, Peterman completed 378 of 619 pass attempts (61.1 percent) for 5,142 yards with 47 touchdowns and 15 interceptions.

Cosell compared Peterman to Hoyer, whom he noted, “doesn’t have a gun” for a throwing arm. Hoyer is expected to be the 49ers’ starting quarterback in 2017. Hoyer and Matt Barkley are the only quarterbacks on the 49ers' roster.

“Kyle’s offense starts with the quarterback under center and it’s very detailed and precise and there are very few guys in college football who come from those kinds of offenses,” Cosell said.

Cosell included Miami’s Brad Kaaya as a player with significant experience in a system that translates closely to the NFL.

“They played in pro offenses, so they have some conceptual foundation whereas the other guys have no clue,” Cosell said.

“Theoretically, Brad Kaaya fits. I don’t particularly like the player on tape, but he fits. I think he needs an awful lot of work. That comes down to what a coach feels about the kind of work he needs.”

Kaaya (6-4, 214) completed 60.6 percent of his attempts for 9,968 yards in his three-year career. He threw 69 touchdowns and 24 interceptions.