Worcester now travel to Galway on Friday for the second fixture with Connacht and Ruddock admits his teams must cut out the mistakes and improve.
"You reflect on the game and you ask yourself, how often we were on our own line under pressure? How often were we scrambling in defence? How many tackles did we have to make? I don't think we had to make too many really.
"It was a big Christmas present for Connacht from us, gift-wrapped and three tries off three mistakes really.
"Well done to Connacht for taking them, they didn't need a second invitation and they deserved the victory through dogged defence and making for less errors than we did. We had a lot more ball than them, but there were too many errors.
"We're desperately disappointed, three tries from three big mistakes," he added. "The intercept try is either going to be a try for us or they pick it off.
"The second try a poor pass from their scrum dropped on the floor and their guy hacked it across with his foot, it fell kindly to get outside our chase.
"The luck of the Irish on the day went their way and then we turned the ball over on our own line with a lineout. That is inexcusable and unacceptable from us. We're not hiding away from that.
"But other than that we were never really under pressure so we are disappointed, to look at three things like that and know they ultimately cost you the game. It's our errors and we have let our game slip."
The result left Warriors in third spot in Pool 2 behind Connacht and Montpellier with trips to Ireland and France still to come in the group stages.
And Ruddock acknowledged qualification would be a tall order and he would also look to change his selection in Galway in less than seven days time.
He said: "It doesn't look good for us. It's a blow because we have had a great couple of years in this tournament, in terms of getting to the final and semi-final.
"I am not writing it off totally, but losing two games is going to make it more difficult for us.
"It was a bit of a carbon copy of Montpellier at home, we had all the ball and were a bit loose and made too many errors ourselves. Errors we don't normally have in our game in the Guinness Premiership.
"For example, we had a lineout in their 22 in the second half that we threw in not straight. That is normally a big of a trademark for us, to apply pressure with the maul and possibly even score. Those are the things that let us down.
"There seemed to be lots of energy, but when we come out of the Guinness Premiership, at the moment, it is a bit of a worry that we are not quite on the money.
"It was a very disappointing day for us - we are not hiding from that. We gift wrapped it really with the error count.
"Next week we will now probably play a younger team, get a couple of guys freshened up for Northampton.
"It does look like our focus will change a little bit and we must now make sure we sustain recent performances in the Guinness Premiership."