It isnt just you - Unranked is ACTUALLY harder than Ranked
Look at this and sort by normal games - https://bazaartracker.gg/meta
Almost 25% of all runs in unranked are 'lost' at 0 wins. We all know that means that most of them are conceeded due to getting a bad start. This means that most unranked runs- you will only be playing against the good items because no one is forced to attempt to find a good build out of a bad start.
It completly ruins the pool and all the averages are thrown off. Ranked is actually easier than unranked right now which is a crazy situation. Compare it to the Ranked tab and you will see that 10 wins is pretty much the same %, but there are so many more 'bad' builds in the pool.
Is this balanced out by players being more skilled in ranked? It is hard to say as there is no data for that. I would lean towards it being a factor, but not something that removes this issue.
Certainly - It doesnt help that only 10 wins matter in Normal games, but in Ranked you get a reward at 4/7/10 -> people are happier to not have the perfect build every single time.