A year ago, Celtics guard Isaiah Thomas emerged as a star. This season, he has entered even more rarefied air, emerging as one of the most impactful players in the NBA — a step that has been taken by plenty of players throughout the league, but rarely at Thomas’s age.
Thomas is in his age-27 season (he turns 28 in February), far from old but past the point at which many players — even stars — have established their performance levels. As the high school-to-superstar transitions of surpassing talents such as Kevin Garnett, Kobe Bryant, and LeBron James have shown, NBA players tend to establish themselves quickly.
A number of studies on basketball aging curves suggest that hoop stars arrive at (or near) their peaks around their age-24 or age-25 seasons and then sustain them through their late 20s. Of the 31 players who have claimed the 61 NBA MVP Awards, more than half (16) took home their first Maurice Podoloff Trophy by their age-25 season.
Thomas, on the other hand, is redrawing lines in a way that few have done before him. A year ago, he achieved new offensive heights in averaging 22.2 points per game, a career high. Through 42 games this season, Thomas has boosted that average to 28.7.
In its own right, that scoring average is dazzling. In the last 50 years, just two other Celtics have scored at such an outrageous rate through half the season. In 1970-71, John Havlicek averaged 29.1 points through 41 games, and in 1987-88, Larry Bird delivered 29.0 points through 41 Celtics contests. (Like Thomas this season, Bird missed four of those 41 games.)
Yet a broader view suggests that Thomas is doing something even more unusual.
Since the introduction of the 3-point shot in 1979-80, there have been 86 players who scored 20 or more points per game in their age-26 seasons. Of those, Thomas’s increased output from his age-26 to his age-27 season is the third largest, behind only Bryant (who went from 27.8 to 35.4 as a 27-year-old, an increase of 7.6 points) and Stephen Curry, who went from 23.8 in his first MVP season of 2014-15 to 30.1 last season as a 27-year-old.
Yet Bryant poured in 30.0 as a 24-year-old and Curry scored 24.0 as a 25-year-old. In other words, one can make a case that no player who’d already reached the 20.0-ppg plateau so drastically raised his scoring bar more than Thomas has this season.
In surpassing an already impressive career high by 6.5 points per game, he is taking a late-20s leap with few precedents.
Of course, it would be one thing if Thomas were simply scoring like crazy while showing diminished discretion in his shot selection. But the opposite has been the case, much as it was in Curry’s spectacular improvement from 2014-15 to 2015-16.
Thomas is setting career percentage highs for field goals (46.0), 3-pointers (38.5), and free throws (91.0). Yes, he’s taking more shots than he did in 2015-16, but that increase in quantity seems to be following from improved quality.
That helps explain why his Player Efficiency Rating (PER, a catch-all statistic meant to encompass all of a player’s contributions, in which 15 represents a league-average per-minute contributor) has gone up from 21.5 last season to 27.1 this year — an increase that is, once again, the largest since the advent of the 3-point line by a player who’d already reached a 20.0 PER rating.
Win Shares, likewise, attest to the rarity of Thomas’s step forward. He’s on pace for 12.6 Win Shares, which would join an age-27 list that reads like a who’s who of NBA royalty over the last few decades.
Of the players who achieved 12.0 Win Shares at age 27, just two — Hall of Famer Bernard King and former Celtic Dana Barros, who exploded for 20.6 points per game en route to 12.7 Win Shares in 1994-95, a mark that more than doubled his Win Shares for any other season of his career — reached that threshold without ever having surpassed 10.0 Win Shares prior to their age-27 season.
Through a half-season, Thomas has performed at an elite level. It is a transformation that would have been difficult to forecast not only while he was buried in an overcrowded Phoenix backcourt two years ago but also last year, when it would have been reasonable to assume he’d arrived at something approximating his peak.
Instead, Thomas saw his arrival in the land of very good as not a destination but a springboard to something even more impressive. He has offered a reminder that not all players age equally, and that breakouts have the capacity to surprise rather than stick to a schedule.
Follow Alex Speier on Twitter at @alexspeier.