TEMPE, Ariz. -- Last season, the Arizona Cardinals' passing game was a shell of its former self from just a year before.

In 2015, the Cardinals boasted a potent, high-octane, deep-ball-throwing passing game that was the envy of the NFL. It was ranked second in passing yards per game and first in passing yards per play. It helped the Cardinals set six franchise records and propelled them to a 13-3 record and a berth in the NFC Championship Game.

A year later, the air was taken out of that high-flying aerial attack. It was all but grounded. The Cardinals were ranked ninth in passing yards per game and 23rd in passing yards per play. The passing game struggled to get going seemingly all season, leading to an underachieving and disappointing 7-8-1 record that left the Cardinals watching the playoffs from their couches.

A year after he finished with 65 catches for 1,003 yards in 2015, receiver John Brown's yardage total was divided almost in half -- 517 yards -- and he had just two touchdowns on 39 catches as he dealt with two major health issues: being diagnosed as a carrier of the sickle-cell trait and having a cyst on his spine.

Is it a coincidence the passing game suffered the same year Brown suffered? Probably not.

Brown showed last season that he's the X factor to the Cardinals' passing game. In training camp, coach Bruce Arians said as much.

"When you take that explosive, down-the-field play out of there, it's a huge part of it," Arians said.

But the proof is in the numbers.

The output of the Cardinals' passing game was down about 11 percent last season. It produced 28 touchdowns in 2016, seven fewer than in 2015. And the Cardinals' average yards per attempt dropped last season to 6.85 from 8.5 the year before. But those numbers weren't all Brown's fault. Jaron Brown went down midseason with an ACL injury. Michael Floyd underperformed. And quarterback Carson Palmer experienced arm fatigue, a solution for which wasn't figured out until November.

"It just kind of limited us in ways," running back Andre Ellington said about last season. "We missed [John Brown's] presence down the field, things like that. He's just a playmaker. Not having a playmaker out there, that's what we missed."

Brown didn't stretch the field last season the way he did in 2015, when he caught eight passes that traveled at least 20 yards in the air for 379 yards. He averaged 47.4 yards on those catches and ran for 115 yards after the catch. Last season, he had three such catches for 71 yards, an average of 23.7 yards per catch. And he ran for just three yards after the catch. Three.

That wasn't the John Brown the Cardinals were used to seeing.

The 2016 John Brown might not be on the field in 2017 as he continues to figure out how to manage his body. He missed most of training camp with a quad injury but he's been healthy -- or close to it -- the past two weeks.

"I'm hoping I can be 100 percent, but it don't matter," Brown said. "As long as I can push through it and do what I did [against Atlanta in the preseason], it's good enough. But if I'm 100 percent, I feel like I can give it an extra boost and help a lot more."

Brown caught two touchdown passes in the first half against the Falcons on Aug. 26, proving that when he's healthy enough, he can make an instant impact. And when he is healthy and making plays, the Cardinals' passing game is "a lot different," Palmer said.

With Brown on the field in 2015, Arizona threw for 3,831 yards and 24 touchdowns. Last season that number dipped to 2,324 and 15 touchdowns.

Without Brown in 2015 -- which wasn't often, just 91 snaps -- the Cardinals threw for 785 yards and 11 touchdowns. Last season, in 295 snaps without Brown, Arizona threw for 1,812 yards and 13 touchdowns.

When he is healthy Brown has no weaknesses according to fellow receiver Larry Fitzgerald. Palmer agreed.

He can run every route on the route tree. He can make the difficult catch. He can keep his feet in bounds on sideline plays. He can take a short pass and break it for a long gain.

"He's one of our better receivers," Palmer said. "And any time you lose that guy, things change. He means a ton to us."

The Cardinals' offense thrives when Brown is at his best, taking the top off defenses.

"When he's able to stretch the field like's capable of doing, it opens up everything," Fitzgerald said. "It opens up for David [Johnson] to run his choice runs, Jermaine [Gresham] running his ... routes. Me working the zones. It creates just so many more opportunities for his teammates.

"We all need Smoke to be Smoke. I know he wants to be playing at that level and he’s capable of it."

Brown's impact on the run game was evident in 2015. With him on the field that season, Arizona ran for 1,511 yards and eight touchdowns, averaging 5.4 yards per carry on 298 carries. Last season with Brown on the field the Cardinals ran for 760 yards and six touchdowns, averaging 4.6 yards per carry.

A healthy Brown can make life tough for defensive coordinators.

"Pick your poison," Cardinals offensive coordinator Harold Goodwin said.

That's how the Cardinals hope this season will be with their top four receivers -- Brown, Fitzgerald, Jaron Brown and J.J. Nelson -- all healthy. Add Johnson to the mix and the Cardinals could overwhelm defenses on a weekly basis.

Arians feels good about this offense whether John Brown is on the field or not. But he adds "another element," Arians said.

"I like where we are," Palmer said, taking a cautionary approach to evaluating this season's passing game. "It's hard to compare form year-to-year at this time, but I really like where we are with the receivers, obviously, but with the tight ends, too."

Brown feels more empowered this season as a fourth-year veteran to speak up about his health, especially when he believes it's affecting his performance. He's praying that it won't come to that. His goal, he said, is to play the entire season.

If Brown can stay healthy for an entire year, the odds are in the Cardinals' favor that their offense looks more like 2015 than 2016.

"When we're hitting at 100 percent, on all cylinders, the sky's the limit for this offense," Goodwin said. "And that's what we got to be on Sunday. We can't come out fiddling around, screwing around and then not playing fast. So hopefully we can stay healthy the whole year, knock on wood.

"It should be an exciting season for us."