Its not major. But unlike the 2004 AUS winning team, their top 6 didn't have every batsman perfect/fairly solid vs spin (McKenzie & Prince in 08, Prince, Dumminy where the vulnerable blokes). Compared to AUS in 04 who all of Langer, Hayden, Katich, Martyn, Lehmann/Clarke, Gilchrist porved their solidity againts spin after past series failures.
In both series when SA encountered real turners in Kanpur (which wasn't a minefield, this was perfectly normal turner) & Kolkatta they collapses to spin i& India came back into the test, when going into both those test SA had the series in the bag.
They didn't need a spinner since they had the pace attack who controlled the IND batsmen for the majority of those two series like AUS pace attack in 04. Since historically its generally always pace that has won in IND - the role of spinner is to be containing. Its the batsmen failing @ crucial points againts the spin test, which prevented them from winning both series.