"It bothered me a lot. Not going to lie," Barrett told reporters, including Stefan Bondy of the New York Daily News. "I really don't understand why I wasn't on it. But it was motivation for next season.
"It was good to have an extra chip on my shoulder and just prove myself even more."
Selected third overall by the Knicks in 2019, Barrett put together a respectable rookie campaign. The Duke product averaged 14.3 points (fourth among all first-year players last season), five rebounds, and 2.6 assists in 30.4 minutes per game.
But the 20-year-old struggled with multiple facets of his shooting: His 40.2 field-goal percentage ranked 66th among 2019-20 rookies (without factoring in statistical qualifiers), and he shot just 32% and 61.4% from 3-point range and the free-throw line, respectively.
Barrett did show slight improvement from long range toward the end of the year, though, improving his 3-point stroke to 36.6% while scoring 17.2 points per game in the Knicks' final 10 contests.
He acknowledged he still has plenty of time to work on his shot.
"I'm actually encouraged to know I kind of started at a really low point, so the only way to go is up," Barrett said. "Not really worried about that stuff at all.
"Whether it's shooting from the field, some NBA superstars in their rookie years, they didn't shoot well from the field. I shot better than some NBA superstars shot in their first year. So that doesn't bother me at all."
Ja Morant and Zion Williamson - Barrett's former Duke teammate - headlined last season's All-Rookie first team along with Kendrick Nunn, Brandon Clarke, and Eric Paschall. The second team featured Tyler Herro, Terence Davis, Coby White, PJ Washington, and Rui Hachimura.