Speaking to the Sporting Life, the City manager said: "We missed a good chance just before half-time to get ourselves back in the game. Aron scored, the game plan was working and to me there was only one side that was going to go on and win it.
"The sending off totally changed the game. That sort of indiscipline is just poor, poor behaviour. It is not going to be tolerated.
"It's been a problem in the past that we've been too soft - and I'm not soft. I don't want soft players, I don't want stupid players and I don't want indisciplined players.
"We don't do that any more and hopefully that will be a lesson to us going forward.
"He's kicked the ball away and you can't do that at Millwall, where referees are put under pressure by the crowd.
"You just can't do that - you have to be tough mentally, not get silly, not argue with referees, just do your jobs and that's not happened.
"I thought it was only a matter of time before we wrapped it up but being a man down caused us all kinds of problems.
"But with four games gone and seven points, I guess you'd say that's steady.
Match Report http://www.coventrycity-mad.co.uk/rprt/mtch/city_put_to_the_slaughter_in_lions_den_552640/index.shtml