"I was pretty pleased with how we did in the first game," noted Shanahan, who not only was making his head-coaching debut but was doing so while also serving as the offensive play-caller. "I can't lie: There's a lot more to think about."
Shanahan cautioned that will be the case for former collegiate standouts Thomas of Stanford and Foster of Alabama. But for one night, their activity on the field far outweighed any mental mistakes that inevitably accompany a rookie in his NFL debut.
Thomas, the No. 3 overall pick in the draft, was all over the field in 28 defensive snaps, which equaled the most among 49ers defensive players. He pressured Chiefs quarterback Tyler Bray into an interception, nearly had a sack, and was a disruptive force at the line of scrimmage on a 49ers defense that dominated the second half of the 27-17 victory.
"I think you guys all saw he definitely got noticed out there, caused some pressure on the quarterback," Shanahan said of Thomas. "He ran to the ball, had a big hit on the sidelines, and I thought it was good to see."
The versatile Thomas, a potent pass rusher on the edge, demonstrated his versatility by moving inside at times and remaining an eye-catching force.
"(He's) just a different change-up for (offensive) guards," Shanahan explained. "We've got some big, long guys (the guards are) going against. So, we get Solomon in there, who I think plays a little bit quicker and has a little bit different type of pass rush. It's a good change-up."
Equally important, Foster shifted inside to NaVorro Bowman's spot for 14 of his 27 snaps and served as defensive play-caller, a role not often trusted to a first-game rookie.
"He wasn't perfect by any means in all of his alignments and stuff and getting in the right gaps," Shanahan noted. "But he showed definitely why we wanted him. He definitely flies to the ball. He's a square hitter, a good tackler.
"I think the more he plays, the better he's going to get."
Shanahan hopes the same is true for himself. He admitted afterward being a head coach and coordinator at the same time was a dizzying experience.
"I'm trying to study pictures (of the previous offensive series) and get my calls right for the next series, but I'm also glancing (at the defense on the field) and having to pay attention to the clock and thinking about replays and all the situations that are going on," he observed. "Another tough thing is you've got 90 players out there. How are you using them? How long are they staying in? Then you have a few injuries.
"So, it's pretty hectic. I'm glad we've got three more (preseason games)."