The first thing you notice about Marcus Johnson is his frame. He's listed at 6-foot-1, 204 pounds, but numbers don't do it justice. There's a thickness to it, a natural-looking strength. Last March, in front of an audience of NFL scouts, he completed 22 reps on the bench press, which would have been the highest total by a wide receiver at an NFL combine since 2015. Except, Johnson didn't do it at the combine. He wasn't invited.

The second thing you notice about Johnson is his mentality. Or, at least, the way it manifests itself in his actions. Take Tuesday, for instance. Johnson had a very good practice, the latest in a line of them that stretches back to spring mini-camp. While working in with the first-team offense — veteran starters Alshon Jeffery and Torrey Smith had the day off — the receiver who turns 23 Saturday spent the three-hour session as a favorite target of Carson Wentz, capping off his day with a vertical route that left cornerback Patrick Robinson looking like he was moving in slow motion. Johnson then proceeded to get behind Rodney McLeod and haul in the perfectly placed pass. After it was over, he peeled off from the flow of bodies to the locker room and spent the next 10 minutes alone on a far field, where he repeatedly lined up against an orange tackling dummy and practiced the footwork and hand-fighting technique he uses to get a clean release off the line of scrimmage.

[Jeff McLane's Tuesday practice observations: Marcus Johnson catching on]

"You want to critique yourself more than you give credit," Johnson explained after the remedial work, which he capped off with some pass-catching work on the JUGS machine.

The short story is this: Johnson has an NFL frame. He has an NFL mentality. The 4.38 40-yard dash he ran at Texas' pro day in 2015 shows that he has NFL speed. And, thus far, he's been making the kinds of catches that command the attention of NFL coaches and players. "He's making plays,"  Wentz said after Tuesday's session.

Whether all of that will equate to an NFL job depends in large part on a couple of factors that are only partially within Johnson's control.

The first is the numbers game, a variable that every player of his profile confronts. The Eagles signed two receivers this spring, Jeffery and Smith. They added two more in the draft, Mack Hollins and Sheldon Gibson. Factor in Jordan Matthews and Nelson Agholor, and the depth chart gets crowded fast. The Eagles carried five wideouts for most of last season. That was a bit of anomaly, as teams often carry six. Seven isn't unheard of, but six is the assumption.

[Bob Ford: Mack Hollins works to be special as a receiver, too]

At the moment, the outlook has Jeffery, Smith, Matthews, Agholor and Hollins as virtual locks. Heading into training camp, the assumption was that the sixth spot would go to Gibson, the fifth-round speedster out of West Virginia. But Gibson has had an almost unprecedentedly difficult time catching the ball throughout training camp, even in individual drills. Another player vying for a spot is Bryce Treggs, who spent all of last season on the 53-man roster. Greg Ward, the former Houston quarterback, could also be a factor, although the practice squad might be a more likely destination.

Despite the numbers, Johnson's chief concern at the moment is keeping his body healthy enough to stay on the field. That's been a challenge over the last couple of years. First came a high ankle sprain against Notre Dame in the season opener of his senior year, an injury that haunted him throughout the rest of the schedule. After exploring the possibility of an injury redshirt, Johnson realized he had little choice but to load up on painkillers and play through the injury, which left him a hobbled version of himself. By the end of the year, he'd caught just 12 passes for 130 yards, scuttling any chance he had of getting drafted and leaving his NFL fate hanging in the balance of his performance at Texas' pro day.

"When I think back on that day, I remember there was so much mental pressure on myself because I knew that would carry more weight than my senior year did," Johnson said. "If I don't put up the numbers I put up at my pro day, I might not be here right now. There's no telling where I'd be."

That he would still be here was no sure thing even after the Eagles signed him as an undrafted free agent. On the first day of full-pad practice last training camp, Johnson suffered a quad injury that kept him sidelined for most of the rest of camp. Nevertheless, the Eagles kept him on the practice squad to start the season, then, after releasing him, brought him back in December.

"It was just a series of unfortunate events, but it happens," Johnson said. "You battle through it. Like I always tell people, I know what I'm capable of. This situation right now is a blessing and I have to continue to take advantage of it and stay on top of my body."

There's a lot of time between Aug. 1 and Week 1. At the very least, No. 84 has become a number to watch.