TEMPE, Ariz. -- KeeSean Johnson, now a promising rookie receiver with the Arizona Cardinals, had yet to blossom into a college prospect, let alone a future NFL player by the start of his senior year at Palo Alto High School in Northern California.

But during that final season, Johnson capped a growth spurt, going from 5-foot-4 when he entered high school to 6-foot-2. His voice finally dropped. And he started to shine on the field.

So when everything started coming together for Johnson, his older brother, Vince Miles, made sure colleges took notice. Miles didn't want his younger brother to slip through the cracks the way he had and he diligently began compiling a highlight reel.

"Not a lot of people have big brothers that are willing to do things like that, on their free time, go out there and make their brother a highlight tape to help him get to college and where he wants to be," Johnson said.

Without that tape, the Cardinals might be looking at someone else as their No. 3 receiving option.

Getting KeeSean noticed

Johnson didn't start as a junior at Palo Alto, finishing that season with 15 catches for 266 yards and a touchdown, according to Max Preps. A far cry, at that point, from a college prospect.

During his senior season, though, he had 58 catches for 1,015 yards and 14 touchdowns in 12 games. But he still wasn't getting serious looks from schools. Instead of hard recruiting pitches, he was getting form letters in the mail.

So Miles began cutting clips from Johnson's games with the goal of compiling a highlight reel to send to colleges after the season. Every week, Miles would watch Johnson's game film, cut and crop the plays he liked, and save them for the reel.

Not only was it helping Johnson, it was helping Miles.

"I was like, 'OK, I'm still needed in football in some way. I can still help my brother get to where he wants to get to,'" Miles said.

Miles had been through the process himself. When he was coming out of high school in the Bay Area in 2011, Miles thought colleges would come find him. But they didn't. He didn't know back then that he needed to market himself to earn a scholarship.

Eventually Miles walked on at the University of Arizona as a safety in 2012 and played in every game as a freshman before a neck injury the next year derailed his career.

That injury coincided with Johnson's senior season at Palo Alto and allowed Miles the time to help out his younger brother. At the end of Johnson's senior season, Miles sent the highlights he had compiled to the recruiting coaches at 50 schools around the country, including every Pac-12 school.

Miles did everything he could to make sure coaches saw Johnson's tape, including calling in a few favors. He reached out to his former coaches at Arizona, and also called an old friend, Davante Adams, who now plays for the Green Bay Packers. They grew up together in Palo Alto and their families were close. Adams was starring at Fresno State when Miles called asking if he'd make sure his position coach, Ron Antoine, watched Johnson's tape.

Adams did.

The Fresno State staff discussed Johnson after seeing his film, former head coach Tim DeRuyter said. They relied heavily on Adams and their connections at Palo Alto High School.

"I think it was a situation like, 'Hey, let's bring him in. Let's get a feel for what kind of guy he is,'" DeRuyter said. "We'd already talked to people around him and then getting to know him and his family, it was like, 'This is our kind of guy. Yeah.'"

On tape, DeRuyter saw a "really athletic, smooth" receiver with "excellent ball skills" who was "competitive." Johnson needed to bulk up, but DeRuyter saw a slighter version of Adams -- who was drafted by Green Bay in the second round of 2014.

"I knew he'd develop into being a really good player," DeRuyter added.

In the end, Johnson received three offers: San Jose State -- where Miles had transferred -- as well as Sacramento State and Fresno State. He committed to the Bulldogs two days before signing day.

Cardinals 'thrilled that nobody liked Keesean'

Miles made sure Johnson watched film constantly at Fresno State, a trait that Johnson has carried with him to the NFL. Last season Johnson came in on Mondays, the team's day off, to study. Sometimes he would see things on the screen that could be added to the game plan, said wide receivers coach Kirby Moore, who coached Johnson during his final two seasons at Fresno State.

The work paid off. Johnson caught 172 passes for 2,353 yards and 16 touchdowns during his final two years with the Bulldogs.

Johnson's draft grade was knocked because of his 4.6 second 40-yard dash time, but the Cardinals had him rated as one of the two best route runners in this year's NFL draft. When he was still on the board in the sixth round, the Cardinals wasted no time drafting him.

But Johnson isn't slow, says Cardinals receivers coach David Raih, who is quick to point out that Hall of Famer Jerry Rice ran a 4.71.

"We're much more into route ability and catch ability," Raih said. "So we're happy. We're thrilled that nobody liked Keesean. We loved him and we loved him right from the beginning.

"His tape showed it. He's been producing for a while. This is not new."

In three preseason games, Johnson has caught 12 passes for 137 yards, showing off the relationship he's developed with Cardinals rookie quarterback Kyler Murray.

"I think the quarterbacks, all of them, have confidence in him that if they get it his way, he's going to make a play for them," Cardinals coach Kliff Kingsbury said. "Does a nice job coming back to the quarterback, really friendly on all of his plays. And that's been exciting for us as a staff to see a young guy accept the challenge and really get better every day."

Johnson has established himself as a strong possibility to be the Cardinals' third receiving option when they start the season Sept. 8 against the Detroit Lions. And his older teammates have noticed.

"I mean, KeeSean's just so smooth," Larry Fitzgerald said. "He has really no glaring weaknesses, runs all the routes really well, got great ball skills, late hands, really good in press, knows how to run routes in off coverage. So, this is about reps for him, just continue getting him comfortable out there and be able to play at a high level.

"Kyler is already comfortable with him, as well, so that's an added bonus."

It's a position he likely wouldn't have been in if it wasn't for his brother, who didn't want to take any of the credit for Johnson. But if Johnson hadn't landed a Division I scholarship, it's likely he would've ended up going the junior college route, Miles said.

Then who knows what would've happened?

"I don't think my brother was made to go to junior college," Miles said. "That was the main reason why I put the tape together, because a lot of people get lost in the junior college route. It could be grades. It could just be distractions. It could just be a whole bunch of different things. So, I just never wanted him to go that route."