San Francisco 49ers quarterback Jimmy Garoppolo's much-publicized return to the football field resulted in a surprising 0.0 passer rating. He completed 1-of-6 passes for no yards with an interception. Denver Broncos defenders got their hands on each of the quarterback's first four passes, including the interception on his second pass of the game.

Garoppolo had not played since suffering a torn ACL in Kansas City 11 months ago. The Chiefs, by the way, are the 49ers' next preseason opponent, it is at Arrowhead Stadium, and, yes, Garoppolo will play.

Back to Monday night's interception, head coach Kyle Shanahan finally had a chance to review the game film and noticed much more than just a poor decision by Garoppolo. The coach broke down what happened on the play.

"The one thing that I saw differently once I watched the tape was the interception," Shanahan said. "We got miscommunication in protection, so some guys came in there so the D-end — what's his name — (Broncos OLB Bradley) Chubb, got in there earlier than expected.

"I (initially) thought Jimmy got hit as he was throwing it; he didn't. He got rid of it too early to avoid the hit, and the route hadn't developed yet, so it didn't go far enough down the field.

"We need to do a better job in protection there by getting everyone on the same page, and we need to do better at throwing that ball away, or if you can't, you have to take that sack."

Doing a better job of throwing the football away would have been preferred. Some might question if you want your quarterback, who is coming off a knee injury, to take a sack in a preseason game if it can be avoided. Although, Shanahan admitted on Monday night that he doesn't think much about the knee injury anymore.

"I forget that his knee is hurt," Shanahan said after the game. "The guy has been healthy since OTAs. We're not worried about the knee right now. We just want to get him out there and get some reps so he can play football. It was good for him because it's a big hurdle to get out there for the first time, but we haven't seen any issues with the knee.

"I would forget about it except that he's wearing a brace. I'm reminded there, but we're not too concerned about his injury. It's about him playing and getting reps with our team."