PHOENIX — Last summer, after another injury-marred season, Warriors forward Kevon Looney was desperate for something — anything — to help him resuscitate a career on life support.

He thought about teammates Draymond Green and James Michael McAdoo, both of whom had used an increasingly valuable skill — the ability to defend multiple positions — to earn meaningful minutes when playing time was fleeting. With that in mind, Looney spent the month of August at UCLA, going against guards in pickup games whenever possible.

It was that drive to become a versatile defender, along with an overhauled diet and a season finally free of injuries, that paved Looney’s rise from seldom-used reserve to important role player. As the league trends toward a position-less brand of basketball, he is carving out his niche as a small-ball center adept at switching off screens to defend guards.

“He’s been a big help for us, especially with teams going small,” Green said of Looney. “He can switch out to guards and keep guards in front of him, and he blocks a lot of shots at the rim. He’s really taken huge strides on that end of the floor, and it’s been pretty amazing.”

When he drafted Looney with the No. 30 pick of the 2015 NBA draft, Golden State general manager Bob Myers saw in him the makings of an elite defender: the big wingspan, the solid footwork, the instincts on help-side defense. It took a while, however, for Looney to get comfortable with the Warriors’ switch-heavy system. In his lone season at UCLA, he had played zone defense almost exclusively.

It also didn’t help that hip surgeries limited his rookie season in 2015-16 to five games. Not accustomed to the grind of an 82-game gauntlet, Looney quickly wore down last season and fell out of the rotation. Team trainers decided to sit him for the playoffs when Looney began to experience minor pain in his left foot in April.

Any chance of a big showing at the Las Vegas Summer League this past offseason ended when an allergic reaction made his eyelids swell, affecting his vision. When Looney flew to Los Angeles in late July, he knew his status with Golden State was tenuous. Some were speculating on Twitter that the Warriors should cut Looney before training camp to free up a roster spot for a more intriguing young player.

Finally healthy, he went on a variation of the Paleo diet and shed 30 pounds from his 6-foot-9 frame. In open runs at UCLA, after games of 5-on-5, Looney often enlisted three guards for some 2-on-2. During those sessions, he came to understand the angles and spacing necessary to stick in front of much smaller, quicker players.

“Me being a young player, you’re just trying to figure out ways to get on the court,” Looney said. “You have a great example in front of you in Draymond, who made a living switching off guys. (McAdoo) was making a living working off the switch and being an energy guy. I wanted a chance to do that.”

The Warriors opened the season with one of the most stacked depth charts in NBA history, making it tough for Looney to earn consistent playing time. That began to change Jan. 4 at Houston. After barely playing for more than a month, Looney posted seven points and a career-high-tying eight rebounds in Golden State’s 124-114 win over the Rockets.

Midway through the second quarter, Looney picked up Chris Paul at the top of the arc, stayed with him to the rim, blocked Paul’s layup attempt and corralled the rebound. Late in the third, Looney cloaked Eric Gordon (who’s 6-4), helping force Gordon to airball a three-point try.

With less than five minutes left, Looney held his ground as Paul barreled through him and was whistled for the charge. Little more than a minute later, with Houston desperately trying to trim a seven-point deficit, Looney helped funnel Paul toward the rim, where his layup attempt was blocked by Andre Iguodala.

It all was enough for Looney to slowly move ahead of Jordan Bell as head coach Steve Kerr’s go-to, small-ball center. After averaging 2.5 points and 2.5 rebounds in 9.8 minutes per game in February, Looney averaged 6.6 points, 4.5 rebounds, 1.5 blocks and 1.2 steals in 21.1 minutes in March. Kerr has taken to starting him against small, up-tempo lineups.

In Sunday night’s 117-100 win over the Suns, Looney showed just how far he has come defensively, defending guards along the perimeter and big men on the interior. Late in the second quarter, seeing that 7-1 Alex Len had a wide-open driving lane, Looney broke from his man at the top of the key to swat Len’s dunk attempt at the rim. It was one of Looney’s four blocks that night, giving him at least one rejection in 12 straight games.

Now, with the playoffs less than a week away, Looney has hushed anyone who questioned whether he was an NBA-caliber player. A free agent in July, he figures to have no shortage of suitors.

“Things have started falling into place for him,” said assistant coach Ron Adams, the Warriors’ defensive architect. “He didn’t start the season with a great window to play even. So, guys like that, I’m happy for and I have a lot of respect for.”

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com Twitter: @Con_Chron

Tuesday’s game

Who: Warriors (58-23) at Utah (47-33)

When: 6 p.m.

TV: NBCSBA

Radio: 95.7