The Reds trailed 2-0 with 20 minutes to play at the Kassam Stadium, but goals from Mamadou Thiam and substitute Kieffer Moore late on to ensure Barnsley remain unbeaten in League One in 2019.
Stendel admitted to having second thoughts about his own tactical decisions, but said his team were not happy with a draw.
“The last weeks where we’ve been winning games and our confidence has been getting better and better every week shows in the dressing room, where we are not satisfied with a draw at Oxford,” he said.
“It’s more than nothing. We wanted three points today and we have one point.
“In the first half, we changed the first eleven a little bit with Kenny Dougall in centre midfield.
“After the game I can say that maybe it wasn’t the right decision to change from 4-4-2 to 4-3-3, but I always know better after the game.
“I was happy with the comeback in the second half. The morale and the mentality at 2-0 was good. We’ll take this point.”
Stendel was keen to praise the performance of Jacob Brown in rescuing a draw.
“He showed from the first moment that he understood what I expected from him today,” said Stendel, whose team go into Saturday’s game with Scunthorpe just a point behind second-placed Portsmouth.
“He fought in every duel and he deserved to assist the two goals.
“It was a good performance from him, his self-confidence gets higher, higher, higher every game and I’m happy.”