Mayock explained on the Upon Further Review podcast (via Levi Edwards of Raiders.com) there were various factors in play that led to their lack of impact, but he added the onus is now on the players to have a strong offseason to set the stage for a better 2021 campaign:
"I was disappointed in the productivity of our rookies, I'll be the first person to admit that. You can make excuses, you can have a conversation why. Henry Ruggs, I think is who he is. I'm not disappointed in Henry; I think Henry has to get better. We knew how fast he is, but he has to get stronger, and he has to get in and out of his breaks better. You got to feel him coming out his breaks more for him to get to the next level, and I think he will, but we have a long-term view on Henry Ruggs.
"[Damon] Arnette was the other first-rounder. In training camp prior to injury, he was playing really well. We were really excited about Damon Arnette. He's instinctive, tough and fast, but concussions, a broken hand, COVID—he's got to take care of business in the offseason. Nutrition, strength coach, consistency of a day-to-day program."
Ruggs was one of six wide receivers taken in the first round of last year's draft. The Minnesota Vikings' Justin Jefferson was the standout with 1,400 receiving yards to earn a Pro Bowl selection.
The Raiders' rookie ranked last among that group with just 26 catches. He added 452 yards and two touchdowns across 13 appearances.
His lack of game-breaking plays came as a surprise after he turned heads with a lightning-quick 4.27-second run in the 40-yard dash at the NFL Scouting Combine.
In November, Raiders offensive coordinator Greg Olson said Ruggs was still working on the finer points of the position.
"We love the speed factor; it's something you can't coach. But the route running and consistency, that we want to see him bring to the game," Olson told reporters. "He's another guy that's been out, just finished up outside here with him working the toe touches, the toe drags on the sidelines. So, it's experience for him and route running."
Meanwhile, Arnette struggled to make a consistent impact while working through the injuries and health issues Mayock mentioned. The cornerback finished the season with 25 total tackles, two passes defended and no interceptions in nine games.
His inability to become an immediate high-end contributor was made more frustrating by the Raiders finishing 26th in pass defense (263.3 yards allowed per game).
Las Vegas will hope both players bounce back in a major way in 2021 as it tries to chase down a playoff berth in the highly competitive AFC, which saw a 10-6 team miss the postseason with seven spots up for grabs.