Complex sentence: McGuinness then masterminded a comprehensive defeat of Kerry in the All-Ireland Senior Football Championship quarter-finals, a result described by the national media as "the most seismic result in (Kerry) since the 1987 Munster final replay defeat to Cork".
Split into simpler sentences: McGuinness then masterminded a comprehensive defeat of Kerry in the All-Ireland Senior Football Championship quarter-finals. This result was described by the national media as "the most seismic result in (Kerry) since the 1987 Munster final replay defeat to Cork".