But Ruddock was full of pride for the manner in which his young side stayed with them and insisted he had not ruled out a semi-final spot as his team prepare to face Harlequins next week.
"We battled hard but we were always up against it," he said. "We had quite a few youngsters involved who are either in our Academy or have been part of it. I knew it was going to be tough when I looked at their bench, the last quarter was always going to be difficult and so it proved.
"We were disappointed by the two tries either side of half-time. We were naive just before the break when we just needed to settle it down instead of giving the ball away.
"But we showed a lot of character to come back and when Sam scored his try we looked as though we would make it difficult for Ospreys, who were the better team. We hoped to sneak a bonus point and make the pool even more interesting. But in the end we gave away too many penalties and allowed them to score a late try.
"We could still make it. We need to rely on London Irish doing a job for us. They are a good team and will be at home. Anything could happen, all we can do is get a win against Quins and hopefully still be in the mix at the end of it.
"It was an important pool game for us - there was no sentiment for me coming back to Wales as I have moved on," he added.
"If I am honest I would have liked to have brought down Pat Sanderson and Dale Rasmussen, Rico Gear, Kai Horstmann, Tom Wood and a number of others.
"I wanted to bring my best team and give them a real run, but in the end they were too strong for us.
"They hadn't scored for two games and if I am honest there has been a drop off in intensity for us in the European competition where we have had freedom to play, and that is with all due respect to the teams we have played in Europe.
"The Ospreys have had tough physical games when there has not been room, that intensity has helped them this week and for us, at times, we were a little bit inexperienced."
Ruddock was also full of praise for young prop Matt Mullan who again caught the eye with one superb try saving tackle on James Hook.
"His performance was no surprise to me. We have been talking about Matt Mullan for some time, he is very much the modern prop and he fits into that category," said Ruddock.
"He has scrummed very well all season and he is able to do so much more about the field, he is phenomenal.
"It was a fantastic effort and an old front row colleague of mine texted me after the game to ask who he was. He is catching the eye."
Warriors saw Chris Latham limp out of the action in the last ten minutes but Ruddock allayed any fears about injury.
"Chris is ok, he just cramped up," said the Director of Rugby. "We had a lot of inexperienced boys on the field towards the end so it would have been good to keep him on but he crammed up so we had to take him off. We missed his presence at the back but he should be fine for next week."