Tight end Darren Fells has impressed coach Bruce Arians of late in practice.

Darren Fells was a professional basketball player who made the transition to the NFL in 2013, so of course there were going to be speed bumps. But earlier this offseason, coach Bruce Arians began to wonder if the Cardinals tight end would ever figure it out.

"It's been a couple years now," Arians said. "It was almost like, 'I don't think the light is going to come on.' And all of a sudden, the light came on."

Arians singled out Fells on Monday morning for an "outstanding" past week of practice. His ability to catch passes – a skill in which his

basketball experience translated – was never questioned, but Fells' blocking had previously been subpar.

"That's the hardest thing for basketball players to ever learn," Arians said. "He's coming off the ball extremely well right now and knocking some people back. He's doing it every day. He'll still make an occasional mistake because of his lack of experience, but he's doing the one thing he needs to do to make the football team, and that's hit people."

Fells said he's gotten increasingly more comfortable both in the sport and in the Cardinals' system.

"I'm just coming out a lot more physical," Fells said. "Plus, (Arians) hasn't really seen me in pads. Once I put the pads on, I'm a completely different person. I've been working on it all offseason, just trying to get better."

The path to a roster spot will still be tough. Arians said it's doubtful he keeps five tight ends on the 53-man roster, and there are three established veterans – John Carlson, Jake Ballard and Rob Housler – as well as rookie second-round draft pick Troy Niklas in his way.

Fells said he's not worried about the depth chart right now. He's more interested in proving he belongs on the gridiron.

"I think I've surprised  a few guys," Fells said. "They see me as a basketball player and not a football player yet. I'm trying to get that mentality out there that I'm a football player now."

SPECIAL SKILLS NEEDED TO MAKE ROSTER

There are heated battles daily as players hope to increase their chances at making the team. Fells is trying to make it at tight end, Jaron Brown, Walt Powell and Brittan Golden are fighting for the fifth wide receiver position while Robert Hughes hopes to hold off Jalen Parmele and others for the fourth running back spot.

When it comes time to make the cuts, Arians said an important factor for those backups will be the ability to contribute on special teams in addition to a regular position.

"When you're the fourth back, the fifth receiver, the third or fourth tight end, (special teams coach Amos Jones) needs to be your best friend, because that's how you're going to make the ballclub," Arians said. "If you're a better special teams player I'm keeping you over maybe a better tight end, or maybe a better running back, because you're going to dress on Sunday and help us. You're going to play 20 or 30 plays."

PARMELE GETS HIS CHANCE

Parmele stood out like a sore thumb at rookie mini-camp in mid-June, a 28-year-old with four years of experience on the field with a bunch of first- and second-year players. He was a sixth-round pick of the Dolphins in 2008, played for the Ravens for three seasons before landing in Jacksonville in 2012.

He was out of football last year and badly wanted another chance at the NFL, even emailing Arians to gauge his interest. Parmele was given his chance, got signed, and now has a shot at making the team.

"That's the guy you pull for all the time," Arians said. "That's what's so hard about cutting players like that, because they give you everything they've got. And they're good players. He can play in this league. He might make our football team because he's finding a niche in special teams."