It had not been the best of days for Niles Paul. The door for NFL franchises to sign free agents was open only a few hours on March 13 before the Washington Redskins, Paul’s team, signed two reputable players at wide receiver, Paul’s position.

The Redskins signed Pierre Garcon and then Josh Morgan, and roughly 20 minutes after he heard about the Morgan addition, Paul’s cellphone rang. He had the incoming number saved as “Redskins Park.”

“I kind of started to panic a little bit, because I thought it was the call that was cutting me loose,” Paul said. “I don’t know. I don’t know how this process works.”

Paul recognized the voice at the other end as belonging to Redskins Coach Mike Shanahan and remained convinced he was moments from being cut. Instead, Shanahan asked the second-year player a question that quickly would alter Paul’s place on the team, not to mention his career path.

How do you feel about moving to tight end?

Two months later, Shanahan would compare Paul to a Hall of Fame tight end, and Paul is spending Redskins training camp adjusting to a new position with his roster spot secured. That would not have been the case had he declined Shanahan’s request.

“Niles is a good athlete; they wanted to keep him here,” Redskins starting tight end Fred Davis said. “And he’s a good special teams guy. At the end of the day, they know they can use him on offense, too, if they need to. I wouldn’t let a guy like that go.”

Paul, whom the Redskins selected in the fifth round of the 2011 draft out of Nebraska, filled in at tight end for the last three games of his rookie season with Davis suspended and reserve tight end Chris Cooley on injured reserve. But Paul said he did not get into a three-point stance during that stint and figured it was just a temporary position change.

Redskins coaches, however, came away with a different impression. They saw Paul’s speed — he ran the 40-yard dash in 4.45 seconds at the 2011 NFL combine — and his blocking ability and believed they could mold him into a dynamic threat at tight end. It wasn’t a conclusion the coaching staff at Nebraska ever reached, but Shawn Watson, Paul’s offensive coordinator with the Cornhuskers, said in a phone interview he’s not surprised the Redskins encouraged Paul to make the transition.

“Whenever we needed something done that was of a physical nature — for example, bringing a receiver in motion and cracking a linebacker — we asked Niles to do it,” said Watson, now the offensive coordinator at Louisville.

At Nebraska, Paul’s weight would climb 15 pounds or so above his playing weight (218 pounds) during the early months of the offseason, when weightlifting claimed priority over cardio work, and this past winter was no different.

A few days before Shanahan called Paul in March, Ray Wright, the Redskins’ strength and conditioning coach, phoned Paul to inquire about the player’s weight.

“I was at 234, but I was scared to tell Ray that,” Paul said. “I told Ray, ‘I’m a little heavy right now.’ ”

Wright kept pressing Paul for an actual number, and finally Paul gave up the number. To his surprise, Wright told him to stay at that weight. After the talk with Shanahan, Paul understood Wright’s directive.

By mid-May, Shanahan was comparing Paul to Shannon Sharpe, who shared Paul’s slighter build — compared to other NFL tight ends — when he transitioned from wide receiver for the Denver Broncos in 1990. Shanahan, who coached Denver at the time, witnessed Sharpe develop into a Hall of Fame tight end.

Redskins fullback Darrel Young faced a similar situation entering his second season in 2010. Young was moved from linebacker — the position he’d played at Villanova before signing with the Redskins as an undrafted free agent — to fullback. While it was jarring at first, Young said he came to view the switch as a sign coaches wanted to find a way to get him on the field.

“I’d sum it up in one word: Opportunity,” said Young, who has been working out with Paul since this spring. “I mean, you got a guy like myself who just wants to be there. Niles Paul was a fifth-round pick. You’re not guaranteed anything if you’re not a first-round pick. . . I’m excited to see what he’s going to do.”

That excitement is widely shared at Redskins Park. Shanahan said Paul already possesses “a good feel” for the tight end position. While Davis and Cooley remain ahead of Paul on the depth chart, Paul takes occasional reps in practice with the first-team offense.

“Now we wait and see,” Shanahan said. “Now we see if he can get it done.” Logan Paulsen is a fourth tight end competing for a spot on the team.

While learning the tight end’s responsibilities in the passing game has been fairly easy for Paul, the nuances of the blocking schemes in the run game have taken longer to soak in. On the first day of training camp, Paul, confused as to which defender he was supposed to block on various run plays, said he looked at tight ends coach Sean McVay at one point and wondered: “Is this really what y’all want me to do?”

Since then, Davis and Cooley have reassured Paul that he’ll pick up the blocking assignments. Paul said he still doesn’t know how he’ll fit into the team’s offensive plans this season, but he plans to use his greatest physical asset — his speed — at every opportunity. He’ll also continue to serve as a vital member of special teams.

Paul grinned last week after an afternoon training camp practice when asked whether he thought he’d still be on the roster had he merely hesitated to accept Shanahan’s offer during that March phone call.

“I think I’d be fighting right now on the team,” Paul said. “I think I’d be a bubble player. But the fact that [Shanahan] had enough respect for me to call me and ask me to move to tight end speaks volumes about what he thinks about me. I just want to keep proving him right.”