Southampton boss Ruben Selles offered no excuses after their shock FA Cup home defeat to Grimsby.
Gavan Holohan scored twice from the spot to stun Saints.
Duje Caleta-Car netted one to bring Saints within contention but they could not avoid a seventh defeat in nine matches in all competitions.
Selles, taking charge of his second match as the new permanent Saints boss, admitted his disappointment but was still keen to apportion blame across everyone fairly.
I'm very disappointed with the performance and the result, we didn't expect that as we prepared and dominated the opening part of the game, but it is difficult when you concede those two penalties," he said.
The first one, there is some errors in the build-up. We then set up everything to come back, because in a cup game this sometimes happens, but when you concede another penalty that shouldn't happen it is difficult. We tried, we scored a goal and had one disallowed, but it was not enough from us.
Both penalties were very, very frustrating for me and the staff. You should not allow this to happen because you do not allow yourself the opportunity to win football matches."
Selles made nine changes to his team that were defeated last time out at Leeds United, as fringe players in his 30-man squad were given a chance to make a point to the Spaniard.
I am disappointed with the whole team, it is not about one player or more. They have been working well but when the moment has come to perform they are not there," Selles said.
We were not robust enough to go through moments in the game and come back, I will not change because I think the players are working well but the disappointment is big for all of us."