Boston Celtics head coach Brad Stevens isn't surprised at the recent showcase of Kyrie Irving's passing mastery, as he's followed the young point guard's career from an early age.

Stevens, who used to coach Butler University, had seen him from the time he played for Duke during his lone year as a collegiate player, and even before then as one of the country's greatest high school prospects.

Kyrie Irving, known as a ruthless scorer throughout his career in the league, has shocked many with his deft passing ability, now averaging 8.4 assists per game in the postseason — a career-high.

So how long has Stevens known Irving had this under his sleeve?

“Since I watched him play when he was 18 years old,” said Brad Stevens, according to Joe Vardon of The Athletic.

Stevens was only a 33-year-old practice coach when Team USA coach Jeff Capel approached him with unequivocal belief: “He doesn’t need to play anymore, he’s on the team.”

“Everybody knew he was the best player there,” Stevens said of Irving, who came to camp as the Gatorade Player of the Year in high school.

The Celtics coach remembers his days coaching in Butler University and game-planning for Irving.

“[Duke] had the Plumlees (Marshall and Miles) rolling to the rim and they had incredible shooting, a bunch of NBA players all around (Irving), and he just picked you apart with the pass,” Brad Stevens said. “I’ve always thought he was a tremendous passer.”

To say Kyrie Irving has made leaps with his passing at this level is an understatement. Throughout his entire NBA career, Irving had only 52 games with 10 or more assists. He's had 21 of those in a Celtics uniform and 20 of them have come this season.