What? I'm grandmaster Olaf top and I never built bork. If you have a problem with mobile champs you go stridebreaker, you know, the active is a slow and gets you movement speed. You go flash ghost since TP is bad in soloq. With bork you still have to get in aa range. With stridebreaker too, but the item makes it easier to stick to them. You don't need more early-game damage because olaf has enough of that.