In my opinion Misty's thoughts are as logical a synopsis as I have seen. It explains some puzzles.
DCI Redwood's 'revelation' moment which made sense of the timeline was nothing to do with Crecheman being identified as being Tannerman ... it was all to do with Crecheman being Crecheman ... and Tannerman remaining to be Tannerman.
Depending on the destination, a fairly logical route to be followed when exiting the creche carrying a sleeping child would in some circumstances involve passing block five.
I think all sides of the argument have been puzzled about Tannerman's direction of travel. DCI Redwood's announcement did nothing to clarify that.
We know that information emanating from many sources was analysed by Grange personnel: "Officers investigating her disappearance have completed the huge task of bringing together and investigating the massive amount of information held by colleagues in Portugal, the United Kingdom investigation and the private investigators working on behalf of the McCann family."
http://genreith.de/MMcC/doku.php?id=operation_grangeWhich in my opinion led the police to expand the investigation in this direction.
The only chance there ever was to locate Madeleine was to widen the net, not too much, just a little ... and to follow the evidence.
It is being done now.
How much better the chance for success would have been had that been done ten years ago.