One of the more stunning statistics in ODI cricket is South Africa's record in Sri Lanka. The teams have now played 12 completed matches on the island. Out of those, South Africa have won one. Their captain in that game was Kepler Wessels, and current chief selector Andrew Hudson opened the batting. In almost two decades since, they haven't even come close to the hosts, and so far in this series, they have been outplayed just as comprehensively.

It has not helped that South Africa's best bowler and best batsman have not played in the series. Dale Steyn was ruled out of the tour through injury, and Hashim Amla missed the first match with neck spasms, before sustaining a grade one tear in his groin while fielding in the second. But another one of South Africa's woes, which has little to do with either player, has been the bane of their ODI game for long.

Spin bowlers Robin Peterson and Aaron Phangiso bowled their full quota of overs on Tuesday, and took one wicket apiece. On the surface, this not have seemed a poor return, but in South Africa's innings, their inadequacy was laid bare. Tillakaratne Dilshan, who is better than a part-timer perhaps, but still no ace with the ball, out-bowled South Africa's frontline spinners and extracted more turn than either. His modes of attack were more creative - flighting several outside off before darting a couple on the toes to finish the over. The visiting slow bowlers persevered on a humdrum line, without major variations to flight or pace, and reaped results that fit their bland exertion. On a pitch as slow as this worn Premadasa track, Sri Lanka's 223 for 9 was always going to be a testing total, even with Amla opening the innings and without the intermittent rain.

Part of South Africa's problem is that their opponents are too adept at defusing left-arm spin. Sri Lankan batsmen are weaned on the stuff and the domestic competitions have lately been inundated with high-quality, left-arm spinners. There are also five left-handed batsmen in Sri Lanka's top eight, who will not be daunted by the ball turning into them, particularly as neither spinner possesses a delivery that spins the other way. So thin are South Africa's slow-bowling stocks, there is also no offspinner to call on apart from the part-time efforts of JP Duminy. Imran Tahir, meanwhile, appears to have been discarded like so many South African slow bowlers before him.

Yet, even given these handicaps, Peterson and Phangiso have hardly made the best of helpful conditions. Rangana Herath may be the finest proponent of the left-arm slow bowlers' craft in the world, but he still should not have more wickets from 12.5 overs than all three of South Africa's spinners combined, who have collectively sent down 44. Herath is bowling in familiar conditions, but he is effective the world over, and adapts his game cleverly and quickly. He is no great spinner of the ball either and his guile, calculation and subtlety may mark the route to progress for the visiting spinners. Their captain might also be persuaded to set more attacking fields in conditions where slow bowlers should be dismissing batsmen.

The action now moves to Pallekele, where South Africa may have some respite on a surface that tends to be faster, bouncier and more seam-friendly than the track they have encountered in Colombo. Their pace attack may set about hiding the flaws in the slow-bowling there, but for a side aspiring to build a cricketing dynasty, that cannot suffice. A greater emphasis on developing spin-bowling talent - at least at the top-level, may light the way, or perhaps a prodigy must be unearthed and moulded to plug the mighty hole in an otherwise impressive ship.

Less than a year ago, they were the top team in all formats, but now they have slid to fifth in the ODI rankings, behind Sri Lanka, and have ceded the top T20 spot to the same team. Their limited-overs woes should serve as an ongoing reminder to South Africa that although they fly through in Tests on their vicious pace attack and a formidable row of batsmen, there may come a day when they succumb to their kryptonite, even in the longest format.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. He tweets here