Cardinals tight end Darren Fells is introduced at the preseason home opener against the Raiders.

Darren Fells had it all figured out, right up until Rob Gronkowski walked into the bar.

In 2012, Fells was 26 years old and recently retired from professional basketball. He had been making good money overseas, but was tired of bouncing around for 10 months a year and yearned for a normal family life.

He returned to the United States that August and visited his brother, Daniel – then a tight end with the Patriots – for a weekend of relaxation. The pair had a late dinner after one of Daniel's preseason games, and Darren was happy to share his new plan: earn two more elective credits to get his college degree and then become a guidance counselor.

"At that point, I knew for a fact that I didn't want to (play basketball) anymore," Fells said. "I would rather do a 9-to-5 and work hard to be able to come home to my family every night than to make a little bit of extra money and not see my family at all."

It was a well thought-out, sound plan – and one turned on its head once Gronkowski, New England's Pro Bowl tight end, and other Patriots trickled into the late-night hub. After dinner, Darren was introduced to many of them, and as he began sizing up players like Gronkowski, his imagination began to run wild.

They aren't that much bigger than me, Fells thought. Maybe I should give the NFL a try.

Thousands of 20-somethings in Boston probably have a similar story, but they wake up the next morning and chuckle. Fells went to breakfast with his brother and their wives and told them he was going to pursue it.

"Being 26 (at the time), that's like halfway through your professional career," Fells said. "I didn't know how much of a shot I had. But a lot of people were coming up to me thinking I was a football player, asking for autographs. It was hilarious. Then it clicked, like, 'OK, I can actually do this.'"

As Fells enters his fourth season with the Cardinals, his unlikely success story is well-known. Despite nearly a decade between football games – one in high school, the next in the NFL -- he has, amazingly, made good on the longshot dream.

Fells was an all-state tight end during his prep days in Fullerton, California, but decided to play basketball collegiately at UC-Irvine, where he averaged 10.2 points and 6.3 rebounds per game in four seasons.

As a 6-foot-7 power forward, Fells wasn't quite tall enough to get NBA attention, but had plenty of interest from foreign professional leagues.

For many basketball players, taking that opportunity was a no-brainer, but for the first time Fells contemplated changing sports. He considered using his fifth year of college eligibility on football and later had a tryout with the Vikings. In the end, the certainty of a regular salary sent him down the basketball path.

"Playing overseas I was for sure making money," Fells said. "I could have easily had a career until I was 38 or 39. Money's great over there – obviously not NBA, NFL money, but you can definitely make a living over there. I know a lot of guys who own a house, living nicely, have a small-time job and don't have to worry about money."

For four years, Fells traveled the world. He originally signed with a team in Belgium, then went to Finland, France, Mexico, and Argentina. But after his stint in Argentina, Fells was burnt out on hoops and headed home. A couple months later came the fateful weekend with his brother.

Daniel's agent helped Darren set up tryouts, and the Seahawks signed him in March of 2013. Fells was ecstatic -- until that August when Seattle cut him. For six weeks, as the NFL regular season roared, Fells sat in limbo.

"I thought I made the wrong choice," Fells said. "I was thinking about, 'What am I going to do now?"

Cardinals General Manager Steve Keim brings in numerous street free agents for workouts every year, and the vast majority fails to make a mark. So when Fells visited in October of 2013, expectations were low.

"When you are looking at a change of position or a change of sports, you're always thinking, your initial instinct is, 'How many of these work out?'" Keim said. "At the same time, he came here and he had the natural physical tools. He moved around well. The concern was, he was already, what, 26 when we signed him? Is it too late in the process?"

Fells was added to the practice squad, still very much a flier, and then re-signed to a futures contract after that season. His NFL viability remained in doubt for much of the offseason, as the transition proved challenging.

"Football really is 80 percent mental, 20 percent physical," Fells said. "That's where I struggled."

Fells went into training camp in 2014 on the roster bubble, but the light bulb came on and he made the team. Near the end of that season, the ascension continued as Fells was moved into the starting lineup. He finished with only five catches for 71 yards as a 28-year-old rookie, but his blocking was something then-starter John Carlson lacked.

Last year he made another leap. Fells started 12 of the 14 games he played and finished with 21 catches for 311 yards and three touchdowns. Three years after sizing up Gronkowski in that bar, Fells was a proven NFL commodity.

"To go from a practice squad guy that you weren't too sure about because there's just so many what-ifs," quarterback Carson Palmer said. "What if we put pads on and he can't block? Well, he's answered that question. How is he going to do in press coverage? He's answered that. He's gotten better each year, and he's really turned in to a better tight end in the league."

The Cardinals re-signed former Pro Bowler Jermaine Gresham this offseason and second-round pick Troy Niklas has made great strides in training camp, so Fells is in a battle for playing time in 2016. Whether he starts or not, it's clear Fells has turned himself into a valuable NFL piece.

The interesting part will be how his career plays out in ensuing years. Fells will hit restricted free agency for the first time this offseason at 31, an age when many players have already retired.

That's the downside of starting an NFL career at 26. The upside?

"He didn't have any hits on his body," coach Bruce Arians said. "With sports science the way it is today, I can see him having a four-, five-more year career."

Fells' backup plan hasn't changed. He has his college degree now and will become a guidance counselor when his football days are finished. To him, that feels a long way off. Former Cardinals great Jackie Smith was the oldest tight end in NFL history, playing until the age of 38. Fells wants to surpass that mark.

It seems kind of silly to believe he can play that long. Then again, so was his thinking in that bar in New England.

"It's been a long journey, and hopefully there's a long way to go for me still," Fells said. "That's my hope. Obviously most coaches and GMs don't really see that. I've had four years of football age, but I honestly feel, God-given and body willing, I can play until I'm 40."