Complex sentence: David L. Creasser is a professional rugby league footballer who played in the 1980s, and 1990s, playing at representative level for Great Britain, and at club level for Leeds, and Keighley Cougars, as a, i.e. number 3 or 4.
Split into simpler sentences: David L. Creasser is a former professional rugby league footballer who played in the 1980s, and 1990s. He played at representative level for Great Britain, and at club level for Leeds, and Keighley Cougars, as a, i.e. number 3 or 4.