Rudy Gobert missed game 2 of the Timberwolves playoff series against the Nuggets so he could be with his GF after she gave birth to the couple's first child ... a decision that Gilbert Arenas says was all wrong!!
The T'Wolves announced Gobert would not be available for Monday night's game ... as girlfriend Julia Bonilla had the baby early Monday, and it didn't leave the NBA star enough time to fly back to Denver in time for tip-off at Ball Arena.
Arenas -- who played 12 seasons in the NBA -- did not agree with the 3x All-Star's decision to skip the playoff game .