Complex sentence: Up to 1930, Young was regarded as primarily a batsman who bowled a bit, but that year his bowling developed: he took 66 wickets in County Championship matches alone at an average of 18 apiece, and 71 wickets in all.
Split into simpler sentences: Up to 1930, Young was regarded as primarily a batsman who bowled a bit. But in 1930 his bowling was finally discovered: he took 66 wickets in County Championship matches alone at an average of 18 apiece, and 71 wickets in all.