Complex sentence: William "Willie" Thomas was a Welsh professional rugby league footballer who played in the 1900s, 1910s, and 1920s, playing at representative level for Wales, and at club level for Salford, as a centre, i.e. number 3 or 4.
Split into simpler sentences: William "Willie" Thomas was a Welsh professional rugby league footballer who played in the 1900s, 1910s, and 1920s. He played at representative level for Wales, and at club level for Salford, as a centre, i.e. number 3 or 4.