BKB doesn't counter, I think, enough dmg (bs is mainly physical, is ult = pure dmg and lesh second skill is physical).. If they have blademail, consider to have it tho. Also you had pipe, you were enough tanking 'nuke'. So bkb was not needed. Also BS ult go throught it. The only reason you go for it (that I can see) is if you will tank A WHOLE LOT. Like bs ult you and you don't move kinda : your jobs is to be focused (like DK). A bkb is not 'wrong'. But on everyone? I don't think so since you had the pipe.
For the split push part. They had no real split pusher (natural one with lot of mobility). They could try it. But look :
sparkles wrote:When you face a strong leshrac and bs..ganks, pushed towers and leavergold got em already big
That mean they had no more twr (I guess only t3) and that's it. BS can catch anyone that is going solo split push with low farm. If they split push, they're making themselves more vulnerables. What about they see the split push plan, and they just go for a mid rax, or bottom, or just cut the lane behind the one pushing. So he never get to the top rax for exemple. With a lesh it's pretty easy to block split push from happening. Also, let's say they ignore the split push and dive in their base, catching them up. (Being fed, they kill them quite fast I think). So they end up 3v2, but 2 very fed. So it's easy fight to get rax, if they do buy back, they just got to back and wait for the next time they split push. Kill, no buyback.
It will be easy rax. The only way to win, when your twr are down, it is to wait for them to come at you, let them make the first move, mistake and win the fight by sync all your stuff together. It's a game of patience. Split push later on would be good, I agree on that, but only when dk can 1v1 bs kind of.
So as for bkb, not on everyone. For the split push, yes, once dk is enough farmed (also mirana). Before that you should stay together, defending at base, warding around a lot (sentry and obs) to see them coming at you (when you jungle for exemple).