I think everyone is kind of touching on all the right points..
IMO...
Yes these plays are boom or bust.
Don't be fooled into thinking you HAVE to have a HB with blazing speed, not so. In fact it can be to your detriment.
Very rarely as the OP pointed out do HBs turn the corner and get a good gain, from what I've seen. But I have had success on these plays by using a HB with LESS speed but with quicker linemen that can pull, its no good having a a HB matched up with a quick OLB or secondary, if they get to your HB behind the LOS, you are most certainly going to lose out every time.