There are several questions asked about NFL rookies who make immediate impacts on their respective teams, one of the most common being, "Is the game starting to slow down?"

For rookies, "slowing down" means they are starting to get acclimated to the speed and intricacies of NFL football. They're no longer struggling to grasp concepts and relying strictly on their athletic ability; rather, they're starting to use both in harmony to positively affect games.

For undrafted players like Steven Sims, it's hard to say exactly when that moment occurred. Only Sims himself can answer that. Still, there's no denying what people see, and the game looked awful slow to Sims as he was speeding past defenders in the last month of the season.

In an offense that is full of pleasant surprises from its young players, Sims might have been one of the biggest in the 2019 season. From fighting for a roster spot to catching touchdowns from Dwayne Haskins and Case Keenum, Sims improved almost every aspect of his game and became a vital piece of the offense in the last quarter of the season.

"He becomes more than just a special type of play runner or route runner, now he's incorporated in every down as a slot receiver, or even an outside perimeter receiver," said interim head coach Bill Callahan.

Sims finished the year with 310 receiving yards on 34 receptions, but 230 of those yards came in the last four games of the season. He had at least one touchdown in the last three games against the Eagles, Giants and Cowboys, while hauling in 16 receptions on 29 targets.

To put that into perspective, that is as many receptions and eight more targets than fellow rookie wide receiver Terry McLaurin, who led the team in both categories for the season, during that span. Sims posted a career-high in yards (81) against the Cowboys.

"I'm seeing things faster, knowing what the defense is going to do to me after the snap, things like that," Sims said on Monday.

One of the biggest challenges was learning the offensive terminology, which was sure to be even more difficult considering he, Haskins, McLaurin and Kelvin Harmon were all learning the plays together.

"The play calls are kind of long, they're kind of extensive at times," Sims said. "So [it's about] locking in, listening to everything Dwayne says and slowing it down."

Sims went from appearing in an average of 13.1% of the offensive snaps in the first 10 games to 63% in the final six. A lot of that has to do with an increase in opportunities with veteran receiver Trey Quinn being placed on Injured Reserve two weeks after he sustained a concussion against the Carolina Panthers in Week 13.

But Sims was starting to get more playing time before Quinn was injured. Prior to Quinn's injury against the Panthers, he and Sims played essentially the same amount of snaps (Sims had 23 to Quinn's 22) against the Detroit Lions. At the time, it was only the second time Sims played more than 14% of the offensive snaps.

All the while, Sims was still a contributor on special teams and even took over punt returning duties when Quinn went down. He had already shown his prowess with a 91-yard kickoff return for a touchdown against the Detroit Lions, and he finished the season second in return yards (819), behind only Chicago Bears return man Cordarrelle Patterson, who had 825.

That ability is what got the coaches' attention, and after they saw Sims' speed could do to opponents, they wanted to get him more involved.

"…I really do believe it starts on special teams," Callahan said. "When you're in that role as a returner and you're making big plays and then your role gets heightened and it increases to the point where you're trying to utilize him on different types of specials … and he can do more than that."

And Sims made the most of the extra playing time. He was the only undrafted rookie to total at least five touchdowns in the NFL this past season and the fifth undrafted rookie in franchise history to achieve that feat. He was also the only player in the NFL to record a rushing touchdown, receiving touchdown and kickoff return touchdown.

He was also third among non-quarterbacks on the roster in touchdowns.

"Oh yeah, I love the end zone," Sims said. "Anytime we're down there in the red zone close to the end zone, I'm trying to score. All I think about it scoring."

Sim couldn't name one specific moment where he gained confidence that he could play at the NFL level, but he did say that possibly around the 49ers game in Week 7 is when he started to say, "Okay, I really got this now."

Two games later, Haskins was named the starting quarterback, and Sims quickly became one of his favorite targets.

"Steven is somebody that's really dynamic with the ball," Haskins said. "[He] makes a lot of plays with the ball in his hands. Just trying to get him to understand where he is in the concept, situational awareness and play and of course when he gets the ball in his hands, he's electric. So, just getting him into the offense and where he fits into the roles, and he's doing a good job each week transforming his play -- instead of just being the gadget guy -- to an actual receiver."

With his rookie season now over, Sims is moving on to preparing for next year. He wants to improve almost every aspect of his game, such as catching and route running. He even wants to improve upon his speed, saying that he's "tired of getting caught."

He won't be working alone, though. He has plans to meet with Haskins, McLaurin and the other receivers in Miami, where they'll likely work on their on-field chemistry.

But whatever the future holds for the Redskins and their offense, it's clear that Sims is going to be a part of it.

"I see a bright future for him," Callahan said." I see him being the slot receiver for the Redskins for a long period of time. He's at the tip of the iceberg, in my opinion."