Positional ranks

So I would to know what your opinions are in regards to the positional ranks which were introduced recently. Do you think they are good at pinpointing matchmaking or do you think such feature can be easily abused? So far I have read stories the feature being easily abused if a supposed player don't their wishes role.

As far i can say about the new positional ranks ain't the best deal but you can end quite closer to your previous rank.
On main got d5 and i was d4.
On two new accounts it wasn't so fun.
First one i won 5/5 = silver 4.
Second one i won 10/10 = silver 2.

So as far as i can say you won't go "higher" with a fresh account but you do win 60-80 lp / win until your MMR gets normalized.