The manager excused only four of his team from blame; the rest had delivered an unacceptable, half-hearted and weak performance, he said, as Celtic's European season ended on a pitiful low.
Neymar helped himself to a hat-trick and Gerard Pique, Pedro and Cristian Tello also capitalised on Celtic's timid defending and awful passing. The display was easily Celtic's worst in Europe under Lennon and Barcelona exploited that with their own strongest display of the season. "Barcelona were fantastic - as we expected them to be - but we were very poor," said Lennon. "For some of the players that was an unacceptable performance. It was nowhere near reminiscent of the performances we've put in previously against Barcelona and that's very disappointing. There was no bravery on the ball tonight. We started off nervously and it looked like our heads went down at 2-0.
"There were only two or three players who showed anything - Virgil van Dijk, Adam Matthews and Mikael Lustig, along with the goalkeeper [Fraser Forster] who I'd excuse as well. The rest of the team were very poor and well below the standards they've set themselves."
Lennon himself will face criticism for dropping Charlie Mulgrew and Kris Commons. Mulgrew's free-kick was converted by Georgios Samaras for the meaningless late Celtic goal, and Commons was bright when he came on, too late, at 5-0 down. Lennon said Mulgrew had been carrying a groin problem and Commons was left out because he wanted pace in the side.
"We changed it up and went more defensive - going 4-5-1 - but that didn't stop the blood flowing. We were weak and that's not been like us. That's something I'll need to address and I need to look at going forward. There was no difference to how we approached the previous games against Barca, we set the team out exactly the same way.
"Looking at them before the game, I sensed a little bit of quiet among them so we tried to get them motivated before they went out there. You could see straight away there were some really loose passes in difficult areas and we didn't play anywhere near our strengths.
"We are better than that. I'll have to analyse it and look at the character that was there tonight. There wasn't much of it. I wouldn't say some players gave up, but it certainly looked that way. Some players didn't do their jobs, which they were assigned to do.
"We looked very open in the second half through the middle. That's not normally an accusation you can throw at the players, especially the two centre-halves who have been wonderful for us this season. They were done by very good movement and passing."
The Champions League has brought millions into Celtic again this year but the matches themselves have been bleak. Lennon hinted that he will press the club for significant funds to improve the side before next season's European qualifiers. "It's imperative for us as a club going forward that we try to achieve qualification for the competition each year. Then actually when you go through you [have to] release the pursestrings a little bit more.
"I have got good players I want to work with. I want to make them better and want them to learn from the experience this year."