“Just lettin’ it fly and not thinking too much.”

Those were the words Andre Ingram said at center court after he easily beat Jimmer Fredette in the finals of the N.B.A. development league’s 3-point contest in 2016.

Before this week, that contest, in which Ingram sank 39 of his 50 shots in a half-empty arena in Toronto, represented one of the high points of a long and consistent career for one of the mainstays of a league that rarely gets romanticized in the way that baseball’s minor leagues often are.

But after years of hard work, and a development-league record 713 career 3-pointers, “lettin’ it fly and not thinking too much” paid off when Ingram, at the grizzled-by-N.B.A.-standards age of 32, was told on Monday that he had been promoted from the South Bay Lakers to the Los Angeles Lakers for the final two games of the regular season. According to Basketball-Reference.com, the moment he stepped onto the court for Tuesday’s home loss to the Houston Rockets, Ingram became the oldest American rookie in the N.B.A. since at least 1964.