Grothe's size, speed and trademark ability to break a tackle through sheer strength enabled him to perfectly book-end Parramatta's star studded backline of the early 1980s outside Brett Kenny, Mick Cronin, Peter Sterling and Steve Ella. Along with dual union, and league international Ray Price, these stars formed the nucleus of a side which dominated the New South Wales Rugby League premiership between 1981 and 1986, playing in five Grand Finals, winning four (1981, 1982, 1983, 1986), as well as finishing runner up in 1984, and third in 1985.