That the Falcons had to depend on rookie wide receiver Darius Johnson to make a significant contribution to keep their season from collapsing further was a matter of circumstance, not choice.

Julio Jones is out for the season, and Roddy White sat out the game Sunday against Tampa Bay. Kevin Cone, Drew Davis and Brian Robiskie are listed ahead of Johnson on the depth chart, but that’s not how it played out against the Buccaneers.

“Kevin Cone is a primary special-teams player, (and) Brian Robiskie has only been here a week,” Falcons offensive coordinator Dirk Koetter said. “We felt like Darius could go in and help.”

And so Johnson signed from the practice squad Saturday and played 36 snaps against the Buccaneers the next day. That was the third-most plays among Falcons wide receivers, behind Harry Douglas and Davis.

Douglas is a third-round pick who has played a major role for the team since 2008. Davis, like Johnson, once was on the Falcons’ practice squad, but he had 22 games and 204 offensive snaps on his resume before making his first career start against the Bucs.

By contrast, Johnson wasn’t drafted and didn’t make the Falcons’ 53-man roster out of training camp. All he had to his professional name was a strong training camp, flashes of potential in exhibition games and, since the season started, very few repetitions with the Falcons’ offense.

So while Johnson’s two catches for 24 yards Sunday seem modest, they were important for a Falcons team needing to squeeze every possible yard of production from their short-handed offense. They also were important for Johnson because White’s status for Sunday’s game at Arizona is uncertain, so Johnson could play a lot of snaps again.

Johnson acknowledged feeling “overwhelmed” by his rapid rise from anonymous practice-squad player to No. 3 receiver.

“It really boosted my confidence making it through my first NFL game as a rookie, not really knowing what to expect during the regular season,” Johnson said. “But I think I handled it well.”

The highlight for Johnson came on a third-quarter play when he lined up as one of three receivers in a bunch on the left side of the formation.

Johnson ran hard at the safety to clear space, curled to find a soft spot in the zone and caught Matt Ryan’s pass 1 yard short of the first-down marker. Johnson dove for 2 more yards as cornerback Jonathan Banks closed in to make the tackle.

It’s a routine play for a veteran player, and Johnson made it appear the same.

“It’s really not that surprising because he does that kind of stuff every day in practice,” Koetter said.

Koetter noted that practice-squad players get more practice repetitions than roster players. Most of those repetitions, though, are spent on the scout team mimicking that week’s opponent so the Falcons’ defense can work on its game plan.

Johnson gained the trust of the Falcons during the summer.

“He was a guy who turned a lot of heads during training camp,” Ryan said. “He certainly turned mine. Early on, I didn’t take a lot of reps with him. As he continued to play well through training camp, he would get more and more reps with us. I think he’s a good route runner, I think he’s got really good hands, and he’s faster than what people give him credit for. And he’s smart.”

Koetter said Johnson’s future playing time depends on White’s health and how much Cone has to play on special teams. White didn’t practice Wednesday or Thursday. leaving his status in doubt for Sunday’s game.

At 5-foot-10, 175 pounds and with a baby face, Johnson doesn’t look like the typical football player. But he showed enough potential during the summer that the Falcons kept him on the practice squad and then moved him up when they desperately needed help at receiver.

“I was really happy to stick around because obviously I opened some eyes upstairs for them to want to keep me around on the team and help them to win a few games even (if) on the practice squad by giving them a good look,” Johnson said. “So I was really excited about that. But I’m on the active roster now, that’s even better. I’m loving it.”