Monday's 105-87 setback to the Boston Celtics at Wells Fargo Center was one game 76ers coach Brett Brown quickly wants to forget.

"Last night for me was the most disappointing home game that we've had in a while," Brown said after Tuesday's practice at Philadelphia College of Osteopathic Medicine. "For the first time, I didn't recognize us. That's not this team at all."

The Sixers (2-22) shot 35.5 percent from the field and 14.3 percent on three-pointers and committed 23 turnovers.

The team is dealing with mental fatigue, and it experienced physical fatigue on Monday.

"But like we remind them all the time, the NBA isn't for everybody," Brown said. "The NBA is grueling to be the last man standing and have that DNA and that mind-set and that mental toughness and the physical gift."

The former San Antonio Spurs assistant believes being mentally tough through a grueling NBA season is more important than having someone who can make shots.

"That side of it is so unforgiving," Brown said.

Yet, he adds that most of his players don't have a clue how hard  life in the NBA is.

"So all those things, I feel like my job is to educate them … to first admit it," Brown said.  "Second of all, we got to put our big boy pants on and let's get going.

"That's just life in the league. Maybe it's not for everybody."

Follow and contact Inquirer 76ers beat writer Keith Pompey on Twitter @PompeyOnSixers and on Instagram at PompeyOnSixers