The youthful Power side stuck with the Cats up to half time, but was simply brushed off the ball in the third quarter when the home team slammed through 11 goals to one to set up the 95-point hiding.
"Seeing what Geelong did today, I think, would be a great lesson for everyone," Williams said after the match.
"I have to say at half time we were very positive about our belief in the guys and what we might be able to do, but when it came down to it I thought Geelong were outstanding - they just brushed us aside and made us look like little kids.
"I know it's a pretty bitter pill to swallow right now, but we have to look to the future and keep giving good game-time to these players to make sure that they get experience with such great [opposition] talent around them.
"You learn a lot from those sorts of losses. What you have to do is look at it and say, 'How was it going in the first half?' Did it look like it was along the way of what you wanted? And yes it was.
"Our run and our ability to maintain it was not there in the second half, so certainly we need to work on the ability to sustain it.
"That will be based around getting some more fitness into some of the players and also [developing] mental toughness."
Hard-working defender Alipate Carlile won the praise of his coach with Williams also encouraged to see Robbie Gray and David Rodan back out on the park after extended injury layoffs.
But he struggled to name many players who broke even in their positional battles after half time.
Williams tried in vain from his coach's box to stem the flow of Cats goals in the third term, but said the young side he had taken into the match was just physically unable to comply with his instructions.
"We tried most things except just putting everyone down one end and I'm not really into that," he said.
"We certainly weren't sitting on our hands; we were trying to get something going and for a period there it seemed to click into gear.
"But I honestly thought that our ability to run out the game was really questioned today and that was a lot to do with our selections. We were understanding that we were going down that path.
"We came into the game understanding we had a few players who needed to get game time … and to be 10 points down at half time against Geelong is a very good effort for us."
Chad Cornes suffered a broken nose in a head clash with Darren Milburn, but will be available next week when the Power hosts St Kilda on Saturday night.
