Kyle Shanahan is pretty smart. He knows that if he does something in the preseason, he's giving something for his Week 1 opponent to prepare for.

Or, maybe he's serious about rotating quarterbacks.

The 49ers had a fun wrinkle to their QB dilemma on Sunday: They just had them trade off plays. Maybe that's what we'll see in the regular season. Maybe not.

Will 49ers rotate QBs?

The 49ers weren't necessarily catering plays for Jimmy Garoppolo and Trey Lance. They were just shuttling in and out.

Each quarterback got a rushing touchdown in the 49ers' first two series.

It's incredibly rare for an NFL team to rotate quarterbacks. The Dallas Cowboys rotated Craig Morton and Roger Staubach every other play for a while in 1971, and there haven't been many other instances.

That's why it seems like Shanahan was just planting a seed. The Detroit Lions, who play San Francisco in the season opener, will see that on tape and have to prepare in case that's what the 49ers do. In that way, it's smart.

It might not be so genius to rotate QBs play by play in a game that counts. But we'll see. It would present some challenges for opponents.

Trey Lance could play some without starting

At some point this season, Lance is very likely to start for the 49ers. Third overall picks don't sit all season anymore.

Until Lance takes over the full-time job, he's still probably going to play some. Like the New Orleans Saints the past couple seasons, when they would put in Taysom Hill for Drew Brees for a play or two that took advantage of Hill's rushing ability, Lance will likely have a package of plays early in the season that will be sprinkled in here and there. He and Garoppolo have different skill sets and could stress defenses in different ways.

We'll see soon enough what Shanahan's plan is for the regular season. He has given early season opponents something to think about.