When discussing his NFL debut and why he wasn’t pleased with it, Landon Dickerson broke out a phrase worthy of a motivational poster.

“I could sit here and give you excuses all day, but I believe excuses breed mediocrity,” Dickerson said. “There’s no reason for me to sit here and tell you, ‘This is the reason I did this or that,’ ... I just evaluate what I did and fix it.”

The Eagles rookie offensive lineman was thrust into his first game sooner rather than later, relieving Brandon Brooks at right guard during the Eagles’ 17-11 loss to the San Francisco 49ers on Sunday. His first offensive snap came in the second quarter, when he was bowled over in pass protection by 49ers defensive tackle Arik Armstead. The result was a 91-yard completion to Quez Watkins, but Dickerson’s individual performance was indicative of the up-and-down debut he was in for.

The second-round pick said during a news conference Thursday that he wasn’t satisfied with his performance and shied away from any excuses, whether it be his relative unfamiliarity with playing right guard or his recent return to practice after tearing his ACL last December.

With Brooks on injured reserve with a pectoral strain, Dickerson will get another chance to meet his standards Monday night against the Dallas Cowboys. Eagles coach Nick Sirianni declared Dickerson the starting right guard during his Thursday news conference, citing Sunday’s game as a teachable moment for the former Alabama center.

“It’s going to be Landon,” Sirianni said. “[Sunday] was a good learning experience for Landon. I know he made the corrections, and he’s looking forward to getting out there practicing today to get better.”

Dickerson mostly held up in the run game, but had noticeable struggles in pass protection against the Niners. Pro Football Focus credited him with five allowed pressures, which is the most given up by an Eagles lineman so far this season.

When asked about Dickerson’s showing, Eagles veteran right tackle Lane Johnson said he saw improvement from the rookie as the game wore on.

“Other than the first rep, I think he settled down ... and started playing well,” Johnson said. “It is what it is. Guys get thrown in, you have to adjust and learn on the fly.”

Johnson conceded that he and Dickerson didn’t get many reps together going into the game because he spent training camp working at center more than guard.

After suffering a torn ACL last December in the SEC championship game, Dickerson just recently made a full return to practice last week. He spent all of training camp on the non-football-injury list and was activated to the 53-man roster ahead of Week 1. He was a limited participant in practice until last Thursday and was active for the first time against San Francisco.

» READ MORE: Eagles second-round pick Landon Dickerson a full participant in practice for the first time since being drafted

The Eagles drafted him with the expectation that he’d eventually become a quality backup at multiple positions, but perhaps not this soon after he returned to the field from a major injury.

Dickerson was billed as a first-round talent going into the draft, but injury concerns caused him to slide into the second round. He suffered several significant injuries during college, including season-ending injuries to both ankles and tearing both ACLs.

When asked what surprised him most about his NFL debut, Dickerson said the speed of the game stood out.

“The game’s a lot faster,” he said. “Guys are a lot quicker, smarter, stronger. Everything gets bumped up a notch.”

This week, Dickerson will get the chance to focus solely on playing right guard and improving his chemistry with Johnson and center Jason Kelce, something Dickerson thinks will make a big difference.

“It’s going to be very beneficial to get reps with the first team,” Dickerson said. “Especially getting timing down with the guys, learning how they play, how fast they play, what their footwork is, and getting everything meshed up.

“It’s really just a process of getting to know them and them getting to know me and making that combination work,” Dickerson added.

Johnson agreed that the upcoming practice reps will go a long way in acclimating Dickerson to the right side.

“I think communication is key,” Johnson said. “I think we can accomplish a lot, just from having really nothing to a full week of practice, so that will be big, and we’ll feel a little bit more settled down going into the game this week.”