Look who impressed Jim Harbaugh on first day of Chargers training camp

The Chargers' new facilities in El Segundo buzzed with excitement as training camp opened with a practice going full throttle — minus the shoulder pads. Still, fans at least caught a glimpse of the team's potential.

Much like the fiery spirit of their new head coach, Jim Harbaugh, the energy levels were high — and first-day jitters were evident. Some takeaways from Day 1 of practice:

Johnston a big factor at receiver

Last season, first-round draft pick Quentin Johnston faced criticism for his production. However, with his rookie season behind him, Harbaugh, Herbert and the organization still believe he can be something special.

“He got a bad rap,” Harbaugh said. “It seemed like he was a disappointment in some people’s minds. He hasn’t been at all in my eyes.”

Herbert praised Johnston, highlighting his great attitude, effort and positive presence, and also noting the team expects big things from him. “He’s a great guy to be around,” Herbert said.

On the practice field, Johnston showcases a rare combination of speed, strength, agility, and size, according to Harbaugh.

“He’s going to be a problem for people,” Harbaugh said. “I’ve been nothing but happy with Q.”

Johnston is currently listed as a starter on the team's depth chart along with veteran Joshua Palmer. Others vying for roster spots include Ladd McConkey, Derius Davis, Brenden Rice and DJ Chark Jr.

Justin Herbert back in form

Chargers franchise quarterback Justin Herbert , coming off season-ending surgery on a fractured index finger last season, appears to be fully recovered. The football was coming out of his hand well.

Harbaugh had high praise for his new quarterback, saying Herbert has command of the offense and just needs to focus on being better than the day before.

“He's mastered everything in terms of the offense — the plays, the cadences, and the defensive structure with protections,” Harbaugh said. “The amount of work he's put in is incredible.”

Early in the practice, Herbert and the new receiving corps looked a bit out of sync. As practice progressed, however, they began to connect, especially when they worked against the defense in the red zone.

With veteran wide receivers Keenan Allen and Mike Williams gone, Herbert has had to quickly develop a rapport with his new and inexperienced corps.

“The next step is building time and trust with those guys,” Herbert said. “We’ve had plenty of reps so far, and you come into camp comfortable knowing these guys can be in position.

“I’m really excited to see what these guys can do,” Herbert said.

Secondary, Cam Hart impress Harbaugh

The Chargers secondary matched the energy around the facility, aggressively attacking the football and flying around the field during full-team drills — at times to Harbaugh's dismay.

“I loved the defensive backs,” Harbaugh said. “They were feeling the juice, but it's about controlling your mind over your nervous system. You gotta control that first day.”

Veteran safety Derwin James Jr., the leader in the secondary room, said he was still coming down from the energy of the first practice.

Following practice, Harbaugh praised newly acquired Kristian Fulton, along with younger defensive backs Asante Samuel Jr. and Cam Hart.

Hart, a fifth-round rookie, caught an interception during practice and stood out for most of the day.

Harbaugh noted he has liked Hart’s development since April, complimenting his range, length and instincts. The coach even compared Hart to James, particularly highlighting their strength.

“I love Cam Hart,” James said of his teammate. “I’m a big Cam Hart fan. He’s locked in, and the sky's the limit for him.”

This story originally appeared in Los Angeles Times .