Ben Gibson offered a candid assessment after Boro's 4-2 defeat at Hull City on Wednesday.
"We didn't play the way we wanted to, or should have," he said.
"We're used to being solid, and we weren't. I'll hold my hands up, I've got to do better for some of the goals.
"We tried to be more expansive and creative up the pitch, and changed the shape. But ultimately, we didn't do our jobs defensively and without the ball, and we have to resolve that quickly.
"We scored just before half-time, and maybe the whistle came at a bad time for us - we were on top and had them penned in.
"But we didn't do enough second half, and we conceded a soft goal from our point of view.
"It was far from good enough from all of us, myself included."
Gibson says Boro will keep battling, with Burnley next up at the Riverside on Saturday.
"It's about the team and we won't stop fighting," he said.
"There's eight games and 24 points still to fight for.
"It was a big blow at Hull, but we have to get on with it quickly. It's a massive game against Burnley now.
"We won't stop believing and won't stop fighting."