The Crusaders beat the Highlanders 40-12 at Forsyth Barr Stadium, running away with the game in the final 10 minutes as the Highlanders finished with only 14 players on the field.
''I thought the guys played really well. But discipline, that really cost us. We had one in the sin bin, for what, I don't know. I had a look and didn't see anything. Then we had Ma'a's [Nonu] sending off and that blew any chance to come back at them,'' Joseph said.
''When we were able to play our game and at their end of the field we looked pretty good.
''It cost us, really, 10 minutes in the first half, and then 25 minutes in the second half. You are playing the Crusaders - you need as much ammo as you can get.''
Not surprisingly, the score ballooned near the end when the Highlanders were a man down.
The Highlanders had their moments but lacked that edge and are still bottom of the table, trailing the 14th-placed Kings by two points.
Joseph said the performance of All Black first five-eighth Dan Carter had a majorbearing on the game.
''You have to remember who you are playing. And the difference for me was Daniel Carter. I thought he was outstanding. He made cover tackles, try-saving tackles, scored tries. He kicked everything.
''They were putting pressure on us. Guys start feeling stressed and they have to go look after the ball, while other guys are waiting at first five-eighth and the ball pops out. We had about three of four of those and they hurt us.
''When you go down into the red zone of the Crusaders, you need to take points away from it.''
He said games were about taking opportunities and the Highlanders had failed to do that.
Crusaders coach Todd Blackadder praised the play of Carter and said he was superb.
The Highlanders take on the Hurricanes in Wellington this Saturday, and Joseph said he may look to some younger players in the team.
In other games over the weekend, the Sharks beat the Blues 22-20 in Durban, scoring a try in the dying minutes to win.
The Bulls were too good for the Kings, winning 48-19 in Pretoria, and the Stormers put a serious dent in the playoff hopes of the Cheetahs with a convincing 28-3 win in Cape Town.