My opinion - the Sox thought two things when bringing Robin in:
1. We are going to suck and this will deflect blame - people will not want to blame a fan favorite who is new to managing.
2. People will come to games because Robin is here despite the record.
1 was right. 2 was wrong.
Note - these two thoughts are exactly what the Cubs had when they considered Sandberg and hired Sveum instead - I think they wanted to avoid any chance of Sandberg tanking with the rebuilding project right out of the gate.