“That’s just the NFL. You’re going to go against a dog every week,” said rookie Kendall Fuller, right, here going against one in Dez Bryant on Thanksgiving. (John McDonnell/The Washington Post)

Kendall Fuller’s rookie season has been a baptism by fire.

Some young players gradually work their way into prominent roles. Others get thrown to the wolves. Redskins coaches planned on the former for their third-round draft pick, a cornerback, but scrapped it for the latter.

After sitting for the first three games of the season, Fuller held his own in his pro debut in Week 4 while filling in for an injured Dashaun Phillips. He exhibited good instincts, sure tackling skills and the potential to develop into a force. That was enough for coaches to thrust him full time into the role that they — and veteran defensive backs — describe as the most complex position in the secondary.

Since then, Fuller has found himself in the crosshairs often while covering dangerous receivers. As of late, opponents have played their top receivers in the slot more frequently to avoid Washington’s No. 1 cornerback, Josh Norman.

Detroit Lions wide receiver Anquan Boldin crosses the goal line for the game-winning touchdown with Kendall Fuller hanging on, but it hasn’t been all bad for the third-round draft pick. “You can only learn from it.” said safety Will Blackmon. (Jonathan Newton/The Washington Post)

In the past four games, Fuller has matched up with Cincinnati’s A.J. Green, Minnesota’s Stefon Diggs, Green Bay’s Jordy Nelson and Randall Cobb, and Dallas’s Cole Beasley and Dez Bryant.

“That’s just the NFL. You’re going to go against a dog every week,” Fuller said. “You’ve just got to make sure you come prepared. If you don’t, it’s going to be a long day.”

[Jordan Reed is unlikely to play Sunday, but Jay Gruden is staying mum]

The days have seemed long in recent weeks. Diggs, a second-year pro and Fuller’s former Good Counsel teammate, recorded a season-high 13 catches for 164 yards while matched up primarily with Fuller in the Redskins’ win over Minnesota. Nelson and Cobb took turns lining up opposite Fuller, each recording key grabs but not enough to lift their team to victory.

Beasley and Bryant also alternated in the slot and made big plays — a number of them on third downs — to help the Cowboys to a 31-26 win over Washington.

“That’s part of the position,” Fuller said after the loss. “Guys are going to make plays. You just have to line up and keep on competing. . . . Third-down plays like that, we’ve got to get off the field. Some of those third downs, I didn’t make. So I’ve got to go in, work, prepare better and make sure I make those plays next week.”

The laid-back Fuller talks and thinks like a veteran, his teammates say.

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They credit the lessons of his three older brothers, who preceded him both at Virginia Tech and in the NFL. Vincent Fuller played safety and spent seven seasons in the NFL , Corey Fuller is a wide receiver for Detroit, and Kyle Fuller is a third-year cornerback for Chicago .

Because of his skill set, understanding and pedigree, Redskins officials saw Kendall Fuller as a steal in the third round. Had it not been for microfracture knee surgery, which ended his junior and final season at Virginia Tech after just three games, they believe Fuller would have gone in the first round.

Seven months into his NFL career, Fuller has played more than any other member of his Redskins draft class. First-round pick Josh Doctson, a wide receiver, is on injured reserve. Second-round pick Su’a Cravens is a situational linebacker, and other picks rarely play.

Fuller, meanwhile, is a full-time player, logging 71.8 percent of the snaps since Week 4. He has lived up to the expectations of his coaches.

“I think it’s a little typical of a rookie,” defensive coordinator Joe Barry said. “I think he’s had some ups, some downs. I know one thing: I think Kendall Fuller is going to be a special player in this league for a long time. His maturity, his instincts, his awareness have been really, really impressive for a rookie.”

The jump from college to NFL comes with growing pains for any player but especially for a nickelback because of the intricacies of the position.

[Redskins-Cardinals: Key matchups to follow Sunday in Arizona]

“Nickel is hard in general because the receiver has a two-way go,” safety Will Blackmon explained. “It’s already instantly hard to be in that position. You can be in cover-one, and no matter where your leverage is, they’ll just go [the opposite direction]. You kind of have to be aggressive and be ready to attack the ball at all times. At the same time, you’ve got to have the knowledge of a safety and a linebacker. It’s a complicated position, which is why a lot of the top talented corners will never go in there to play the slot. You know, Deion [Sanders], he would never play the slot. Very few want to go in there.

“So Kendall is doing well,” Blackmon continued. “You’re dealing with veteran receivers, Pro Bowl receivers, so you’re going to have days where they’re going to come after you. It’s just how it’s going to be. The only beneficial thing about it is you can only learn from it.”

Fuller has gotten beaten on pass plays but not by a large margin. He’s often a step or two too late. But that’s correctable, he and the Redskins believe.

“My main thing right now,” Fuller said, “and what Coach [Jay] Gruden has been getting on me for is, I’m there. I’m always there to make a play. But it’s about getting over that hump to actually make it; get there a step faster to get my hand out there to make a play on the ball. I’ve just got to be that much better in my technique. Focus on the little things.”

Said Gruden, “I like the ways he plays. He plays with great effort. He’s a smart football player. He has just got to continue to work on his technique, and I think that’ll come with time. Whether it’s outside leverage, inside leverage, off technique, whatever it is, zone technique, all that stuff is just repetition, repetition, repetition. The more he gets, the better he is going to be.”