As for the chicane where the old part joins the current track, I find it pointless. It could directly join the current track through the hairpin runoff.
I guess they want the downforce level to be about the same as now. If you had the old loop as it was without any chicanes you eliminate the current big stops at Turns 1 & 2. Teams would then shed downforce which makes the run to the current Turn 3 quick, which would push runoff and grandstands back. Didn't Williams clock 378km/h in Baku?
A chicane at the join between new and old would maintain the balance and reduce the need to modify bits of the current racetrack. It would also preserve the overtaking spots we have now.
Edited by Al., 02 July 2016 - 17:50.