At this time of the college football year, the defense is usually ahead of the offense. That was true for Stanford in Sunday’s scrimmage even though its offense is expected to be one of the nation’s best.

That may have been partly because All-America running back Bryce Love put in only a cameo role. And starting center Jesse Burkett was out with an injury — head coach David Shaw said he may not be back until “early in the season.” Also missing was possible starting guard Brandon Fanaika.

But the defense was missing even more players. Cornerback Alijah Holder and linebackers Joey Alfieri and Mustafa Branch were held out as a precaution. Linebacker Curtis Robinson and lineman Dalyn Wade-Perry should be back by the end of the week, Shaw said.

Nevertheless, the defense generally had the upper hand during the first of two open practices in training camp. The second is at 3 p.m. Sunday.

The only touchdown came on a fine throw by K.J. Costello to JJ Arcega-Whiteside. Arcega-Whiteside caught the ball between two defenders 25 yards downfield, then bolted for a 70-yard touchdown.

“That’s obviously the big play of the day,” Shaw said, “but I thought defensively we got off blocks to stop some running players.”

Shaw was happy to see backup quarterback Davis Mills do so well in his first live scrimmage after undergoing knee surgery late in the 2017 season. “He didn’t flinch at all,” the coach said. “He starting to show that complete understanding of the offense, which is awesome.”

Shaw liked the movement of the defense overall. Although inexperienced, the defensive line is “active and getting off blocks,” he said. “It’s been tough to run the ball consistently. We cracked a couple, but defensively our guys are playing at a high level.”

Shaw said Costello “threw some nice balls today when he had the protection.”

Tight end Kaden Smith agreed.

“He’s really matured,” Smith said. “Before, at times, he was just trying to make a play. Now he’s going more by the book. He understands the reads. He understands the defense better. He understands where (all the receivers) are going to be, even if he doesn’t see us.”

Sophomore outside linebacker Gabe Reid looks like a real comer. Defensive coordinator Lance Anderson said that, based on spring ball and training camp, Reid has been the team’s best pass rusher. “He’s done a phenomenal job,” Anderson said.

Reid had a sack Sunday and could have been credited with another one on the TD pass, but officials allowed the play to continue. (As usual in scrimmages, quarterbacks were untouchable. Sacks were called at the officials’ discretion.)

Inside linebacker Sean Barton, back from a knee injury that ended his 2017 season after three games, was satisfied with how the defense played.

“We had some young guys step up and do things that I don’t know if we were expecting,” he said. “They performed well. We’ve got a lot of upside on this team, especially on defense.”

One of those young players was linebacker Ricky Miezan (pronounced mee-AY-zon), a 6-foot-2, 248-pound freshman who had three big hits.

“Great to see that speed to contact from such a big guy,” Shaw said.

Miezan was one of the nation’s best lacrosse players at Episcopal High School in Alexandria, Va., and didn’t play football until his junior year.

Tom FitzGerald is a San Francisco Chronicle staff writer. Email: tfitzgerald@sfchronicle.com Twitter: @tomgfitzgerald