Watch Now: Ben Simmons Scores 1 Point in 76ers Loss (1:16)

For the first time in Ben Simmons' young NBA career, he failed to score a field goal. The 76ers' star faulted no one but himself reflecting on the performance that came during Philadelphia's 108-103 Game 2 loss on Thursday.

"I think it was mainly what I did to myself," Simmons said. "Mentally, I was thinking too much, overthinking the plays. Wasn't just out there, flowing, playing the way that I play, which is free.

"I think, obviously, [the Celtics] have a game plan, I know what their game plan is and I've got to play my game."

Simmons' dud of a game couldn't have been more poorly-timed for the Sixers, who find themselves in a 2-0 hole in the second-round series against Boston. Celtics coach Brad Stevens schemed to disrupt Simmons, who has been one of the hottest players this postseason. And it worked by throwing at various matchups at him -- but Simmons insists his shaky performance was "self-inflicted."

"Mental, thinking too much," Simmons said. "I think the way the Heat played, it was nothing compared to the Celtics. Physically, the Heat were on another level. I'm going to have bad games; it happens. Obviously, it's not the perfect timing. But we're headed home now.  

"We're learning, we're a young team," Simmons continued. "Nobody is panicking in the locker room, nobody's freaking out. We're staying together as a team. We go home and we've got to take care of business."

In 31 minutes on the floor, Simmons notched one point on 0-for-4 shooting, and had five turnovers compared to seven assists en route to accumulating a minus-23 -- the worst plus-minus of any Sixers player.

Philly isn't down and out yet, but as the series shifts back to The City of Brotherly Love for Games 3 and 4, it will need Simmons to shake a slump that, thus far, has uncharacteristically doomed the 76ers in Games 1 and 2.