Unranked accounts MMR should start in the middle of bronze, not silver.
I understand the reason for starting it in the middle of silver, they're statistically average. And that's cool, except that with accelerated leveling, players aren't ready for ranked when they hit 30. Hell, they weren't ready for it before you accelerated leveling. Now you have players with less than 150 games entering ranked for the first time and being eviscerated because they're against players who have 3-4x as much experience as them.
Personally it isn't as much of an issue for me except for dynamic queue fuckering. When 4 people are premade and they have say, a gold 1 and a silver 5, that fucks matchmaking by a huge amount. I end up with and against mostly silvers and while I may perform fine, it's incredibly obnoxious to essentially play a 4v5 because one of my teammates has no idea what is going on. I've seen an unranked account with barely 100 games. They probably don't even know what the current champions names are, let alone what they do. They're practically useless and will just feed the enemy team in most cases.
It's even worse if their unranked player is a smurf. It results in incredibly skewed matchmaking and it just feels awful all around.
Personally, I think that unranked accounts should start at bronze 2 or 3, because if these genuine new players manage to get carried in their first game or two, they will further degrade the quality of matchmaking because they will be against gold and ex-platinum players, who will DESTROY them, and since the first 2-3 games have much more weight than the last few, they will continue to degrade the matchmaking of any game they enter, until they finally fall into bronze. The base starting MMR should be adjusted due to the inexperience of the player. Period. The only reason to have it start in silver is for smurfs, but fuck smurfs anyway. They'll climb retardedly fast regardless, so this doesn't really apply to them.