EAGAN, Minn. -- Brian O'Neill faced constant reminders about what it would take to transform into an NFL right tackle from the moment the Minnesota Vikings drafted him in the second round in April.

There were visual cues. During OTAs in May, O’Neill often worked in a small group with the Vikings' other right tackles as former offensive line coach Tony Sparano barked orders during bag drills. The differences between the physiques of Mike Remmers (6-foot-5, 310 pounds) and Rashod Hill (6-6, 313) compared to the then-barely 300-pound rookie were apparent.

Best of NFL Nation • Assessing legacies of Brees, Rodgers

• Ravens-Chiefs best yet in Baltimore?

• QB Allen looks like star Bills envisioned

• 49ers brace for return to turf of terror

• Steelers getting after QBs at elite rate

The Vikings picked O’Neill 62nd overall because of his length (6-foot-7) and athletic upside (his 4.82 40-yard-dash time was the fastest of any offensive lineman at the combine), but the physical strength and sheer size he needed to add to his frame did not go unnoticed.

And then there was the long-standing perception that O’Neill needed time to develop. He was considered a project, nowhere near ready to play in the NFL. After all, he had only transitioned from tight end to tackle ahead of the 2015 season at Pittsburgh.

But his NFL transition has moved much more quickly than expected over the past eight months. By Week 6, O'Neill was starting on a fill-in basis. Three games later, he had shown enough to supplant Hill at right tackle permanently.

"Well we knew at some point it was going to happen," Vikings coach Mike Zimmer said. "He’s just such a good athlete and he can get to the second level in the run game and so I think the big part about it was how quick he can adapt in the passing game. He continued to get better and better every day. Sometimes he gets out of position, but he’s able to use his athletic ability to get back to recover.

"For an offensive lineman, I think a lot of it in the passing game is being able to recover because you’re going to get some athletic defensive ends and they’re going to put you in a bad spot once in a while. But can you get out of that bad spot and can you still protect the quarterback? And I think he’s done that. It just kind of showed and showed and showed. I guess we just felt like it was time."

The 2018 season was supposed to be a redshirt year for O’Neill. Given the state of affairs with an offensive line marred by injuries and other circumstances that have forced several players to play out of position, the Vikings didn’t have time to waste.

Rookie Brian O'Neill's surprise development has come at the right time for an inconsistent Vikings offensive line. Leon Halip/Getty Images

The team threw O’Neill head-first into the deep end, but his accelerated development is paying major dividends. Since changing offensive coordinators two weeks ago and showing a renewed commitment to running the ball, the Vikings have been able to capitalize on O’Neill’s athleticism to generate more outside zone plays.

According to Pro Football Focus, O’Neill has not given up a sack this season. In Minnesota’s last two games (wins over the Lions and Dolphins), he has been responsible for just one QB hurry and no QB hits. The steps he’s taken in providing protection for quarterback Kirk Cousins have made him one of the Vikings’ most valuable assets on the offensive line.

"It’s not easy to step in at any position but at the tackle position especially, I think it’s a big jump from the college game to the NFL game in terms of the pass-rushers you face and what we ask of NFL tackles as opposed to college tackles in terms of the drop-back game and the number of times we throw it," Cousins said. "He’s still a young player, but I think he’s done a good job of handling what’s been thrown at him and the number of snaps he played this year. I don’t know that any of us expected him to play as much as he has, but he sort of earned that right early in the season. It’s encouraging to have a guy like that who’s playing with confidence and we’re throwing a lot at him and he’s responding."

This season has been an eye-opening experience for O’Neill. The mental and physical wherewithal needed to play right tackle in the NFL are vastly different from those of college. O’Neill has had to learn new technique, new scheme, how to make adjustments in pass protection and what it takes to hold his own against elite defensive linemen on a weekly basis.

Luckily, Minnesota’s starting right tackle from last year has been with O’Neill every step of the way. Having Remmers, a six-year veteran, next to him at right guard has been invaluable for O'Neill's development.

"He’s played against guys and knows what works and what doesn’t," O’Neill said. "He’s executed the same blocks against the guys I’m trying to block. Having somebody who’s done that recently helps. In the middle of a game, if I’m telling him, 'he’s giving me this and what’s a good counter to that,' he’s always a good soundboard for me to bounce ideas off of and talk to and make adjustments throughout the game."