SANTA CLARA, Calif. -- After their bold trade for running back Christian McCaffrey late Thursday night, San Francisco 49ers general manager John Lynch and coach Kyle Shanahan cautioned that while the move was made with an eye toward championship aspirations, it wasn't going to single-handedly get them a Lombardi trophy.

On Friday afternoon, Lynch said McCaffrey wasn't a "magic pill," with Shanahan adding that McCaffrey is "not the only thing we're missing." The message was simple: McCaffrey can offer significant assistance, but for it all to work, others will have to step up, too.

The 49ers received that memo loud and clear Sunday afternoon when the Kansas City Chiefs walloped them 44-23, dropping San Francisco to 3-4 on the season.

On roughly 48 hours of notice, McCaffrey was given a limited workload, playing 21 snaps and finishing with 38 yards on eight carries and two catches for 24 yards. Given the lack of time to absorb Shanahan's playbook, McCaffrey fared well, but the Niners turned the ball over three times, committed 10 penalties for 80 yards, were 2-of-5 in the red zone and yielded 9.1 yards per play, the most their defense has given up in a game since 1965.

"He's not going to be the savior, but he's definitely going to help us out," tight end George Kittle said. "I think these next two weeks are going to be huge for Christian to understand our offense and be comfortable out there not to think at all, just go out and run because that's what he's really good at. Like I said, penalties, turnovers, giving up big plays on defense -- we've got to be better than that. We weren't today. That's how you lose football games."

McCaffrey arrived in the Bay Area on Friday morning and joined the team's practice that day about halfway through after passing a physical so the trade could be made official. At the time, nobody was certain whether he'd even play against the Chiefs, but he spent the rest of Friday and all of Saturday working to understand as much of the offense as possible.

Shanahan and the Niners were comfortable enough with what he learned to put in about 20 plays for McCaffrey and make him active as the backup to starter Jeff Wilson Jr.

After Sunday's loss, McCaffrey credited his teammates and coaches for helping him get up to speed quickly enough to at least contribute.

"This was a weird week for me and for them," McCaffrey said. "I didn't kind of know what to expect. I know that I had a certain list of plays that were up and I think for me mentally this was just focus on everything I can, control what I can control and get rolling. Obviously, losing is frustrating, but I'm still getting to know these guys. I've got to do my job. I've got to make a few more plays here."

Offensively, the Niners had little trouble moving the ball whether McCaffrey was in or not. According to NFL Next Gen Stats, the Niners averaged 5.6 yards per play when McCaffrey was on the field and 6.4 yards per play when he wasn't.

The 49ers finished with 444 yards of offense, but they struggled to finish drives with touchdowns instead of field goals and couldn't keep pace with Kansas City's high-octane offense. In the first half alone, they moved the ball inside the Chiefs' 35 five times and came away with only one touchdown.

"We've got to play better football," Shanahan said. "We had some plays where I thought we had some opportunities and we didn't do well, especially some self-inflicted things, which I think went in all three phases. So, regardless of the players we've added, we have good players I believe, and I think we added another one, but we've got to play better to take advantage of that."

With the sprint to Sunday over, McCaffrey will get his first full week with the Niners to learn the playbook. Shanahan said one of the keys will be teaching him the protections so his role can expand. McCaffrey also noted that much of what he must figure out is timing with his blockers in the team's outside zone heavy run scheme.

Before departing for his next playbook study session, McCaffrey made it clear that nobody is going to wait around for him to catch up.

"Football is football," McCaffrey said. "No one cares if I got here two days ago or if I've been here since April. If I'm out there with a uniform on, I expect to be prepared, and I'm sure my teammates and coaches expect me to be prepared, too. You can't sit there and make excuses and say, 'I haven't had a lot of time.' You've got to get ready to go."