all you have to do is press b again during the flash. you have to press them at the right frames to get the shorten. its a very small window, so especially for people just begining to try it, it can sometimes be very difficult to get it correctly. it is doable tho. just wolf flash around in training mode and try pressing b again after initiating the flash before he reaches the apex, and eventually you will get a shorten. for those who CAN master this, it is an extremelely valuable tactic, as this gives wolf so many options when setting up into side b. not only does he have a crap ton of set ups for it (dtilt, uair, dair, even bair sometimes, shine, and ALL of his throws except fthrow) but he can also angle his side b, which in conjunction with the shortens, allows wolf to utilize these set ups to effectively hit almost any character at any reasonable percent. now this is not the current metagame, but it is what i am 100 percent confident the top of the wolf metagame looks like.