Yallop played for Richmond in the Dowling Shield in the late 1960s. He made his grade debut for the club in 1970–71.

In 1971 he topped the averages for the Australian Schoolboys Cricket Council as they toured Sri Lanka.

1972–73: First Class debut

He made his first class debut in December 1972, making 55 and 21 for Victoria against NSW. His next game, also against NSW, saw him score 15 and 5. Then there was 19 and 58 against Western Australia.

In 1973 he played for Walsall in the Birmingham League. He also played some games for the Marylebone Cricket Club.

Yallop did not play first class cricket during the 1973–74 season. However he was back in the Victorian side over the 1974–75 summer. He played in the Gillette Cup, scoring 2 then made 32 and 48 against Western Australia., 34 and 30 against the touring English side, 21 and 0 against New South Wales, 0 against Queensland 56 and 77 against New South Wales, 23 and 57 against South Australia, and 11 and 38 against WA before making his debut century against South Australia. He ended the season with 5 and 4 against Queensland.

In 1975 he played in England and scored more than 3,000 runs for North Birmingham Club.

Yallop begun the 1975–76 season slowly. He made 38 in a Gillette Cup game then failed against Queensland making 20 and 8 against the 1975–76 West Indians and 21 and 6 against WA. Things turned around with 79 and 62 against South Australia then 108 and 95 against NSW.

These matches earned him selection in the Australian side to play the West Indies in the fourth test. He was picked to replace Rick McCosker who had made 20 runs in six innings. "Its a great thrill and I'm determined to make the most of my chance", said Yallop.

Yallop later wrote in his (ghosted) memoirs that:

The dropping of McCosker angered Ian Chappell and his teammates and I copped the brunt of it. I may have been an unassuming guy at the time, but I was rudely awakened to the facts of life at test level – thanks, or rather no thanks to Chappell and the rest of the team. I was not exactly welcomed with open arms into the team. In fact, I was lucky to discover my locker in the Australian dressing rooms. To top it off, Chappell figured that if I was selected to replace McCosker, that's exactly what I would do... at Number 3. I suppose you could say it was an honour to bat ahead of Ian and Greg Chappell in a test. But I have no doubts that certain members of that team wanted me to fail and there