so I'm guessing that Zandor saw r5 as an effective local reply to |29.r9, so he played |29.r8 instead. He couldn't foresee what was going to happen on the left that might have made |29.r9 work. Disclaimer: my variation is long enough that there is a very good chance I missed something.
now 36.r5 37.p8 38.m5 39.o5 40.p6 41.n7 42.o4 43.g6 44.e9 45.h8 46.g9 47.l6 48.k6 49.j7
so I'm guessing that Zandor saw r5 as an effective local reply to |29.r9, so he played |29.r8 instead. He couldn't foresee what was going to happen on the left that might have made |29.r9 work. Disclaimer: my variation is long enough that there is a very good chance I missed something.