He said: "To go from a performance like last week's game against Bourgoin to this is abysmal and I make no apologies in saying that, as players, we are being paid good money and, if guys heads are not in it, we need to look at why."
"Questions must be asked of us as we've proved the team can perform well so it's not a physical problem – it must be a mental attitude thing that makes us such a Jekyll and Hyde team as it looked like some of the guys' heads just weren't in it tonight.
"We just didn't play our style of rugby and I'm really hacked off about it. We obviously have to take a hard look at what happened out there and make sure we do our best so it doesn't happen again.
JP refused to blame Glasgow's wanderings around the city to an array of training and playing grounds as an excuse on the night which saw them use their third "home" ground of the season.
"We are at home in Glasgow. We've played here before, we train here sometimes and we've won here. Ospreys came up here with a depleted squad and get a result, but that's even more disappointing. I'm pissed off with everyone tonight."