This is still an issue for us and can also be reproduced in the datepicker example Plunker by setting [format]="'MM/dd/yyyy'" and public value: Date = null;. Clicking on the "yyyy" and pressing 2 sets the year to 1.
I hope a fix is coming soon for "yyyy-MM-dd" as we need a reliable datepicker ASAP in one of our applications.
Any E.T.A. for a fixed version?