49ers defensive lineman Arik Armstead took his job home with him last year.

His commitment was rewarded with a breakout season, and a contract that broke the bank.

Armstead’s personal defensive-line coach, Mark Hall, moved into Armstead's South Bay condominium to work with him on technique, film study and nutrition when he was not at the 49ers’ team facility in Santa Clara during the season.

Armstead, who registered nine sacks in his first four NFL seasons, registered 12 sacks in 19 games, including the postseason. The 49ers and Armstead agreed on a five-year, $85 million contract two days before the opening of free agency.

And, now, Armstead is back at work with Hall in Miami, as he looks to take his game to a new level. And his coach believes Armstead has a lot more within his reach.

“Arik left seven sacks out there,” Hall said on The 49ers Insider Podcast. “I really believe Arik could’ve had a 19-, 20-sack season. No doubt in my mind. That’s what you’re working toward.

“He had a good year, but Arik could be much better if he continues to work hard and go in the direction to understand the defensive line position, as well as understand the offensive line position.”

The 49ers decided -- concurrently with locking Armstead up to a long-term extension – to trade defensive tackle DeForest Buckner to the Indianapolis Colts for the No. 13 overall pick in the draft.

Armstead and Buckner, along with Sheldon Day and others, are currently working with Hall at a training facility owned by John Bosa, father of Nick and Joey Bosa.

The work they are doing in preparation of the 2020 NFL season continues while so much of the world has been impacted by the coronavirus (COVID-19).

“We’re working on dynamics, working on strength, working on film, watching plenty of film, and working on angles and stuff, doing a lot of hands and stuff like that,” Hall said. “We can do that in a phone booth. So we have what we need. Everybody here knows what’s expected of them, so it’s not that much of a problem, yet. But it’s getting tougher and tougher by the day.”

[RELATED: Armstead holding raffle to help Sacramento small businesses]

Hall said he expects Armstead, 26, to continue to get more dominant due to his physical skillset and the determination he has shown to hone his craft. Hall said what distinguishes Armstead is his size, strength, agility and work ethic. Armstead has the strongest hips Hall said he has ever seen to go along with incredibly light feet for a man his size.

“He has great leverage for his height,” Hall said. “He’s 6-8 but he plays (like he’s) 6 foot. His D-line IQ is through the roof from thousands of hours of film study.”