See
http://en.wikipedia.org/wiki/John_Crosbie for background on the man whose "Just quiet down, baby" inspired Sheila Copps' "Nobody's Baby":
"A [Progressive Conservative] leadership convention was called for later that year [1983] and Crosbie announced candidacy. At the convention he placed third behind Brian Mulroney and [Joe] Clark. While Crosbie may have been the most popular of the candidates, he was hurt by his inability to speak French. His response that he did not know how to speak Chinese either was not well received. Less notable was the failure of the "John Crosbie blimp" to operate properly during his campaign's demonstration on the floor of the convention."
See also
http://en.wikipedia.org/wiki/Progressive_Conservative_leadership_convention,_1983
which states "John Crosbie, 52, MP for St. John's West, Newfoundland, had been Clark's Minister of Finance in 1979, and known as an accomplished debater with a sense of humour. He was generally seen as the most personable candidate. He attempted to distinguish himself by adopting what he called a 'continentalist' platform, with the centrepiece being free trade with the United States. His campaign was chiefly hobbled by his inability to speak French, and by a political base that was concentrated in the small province of Newfoundland. Before entering federal politics, Crosbie had been a senior provincial cabinet minister in Newfoundland."
(An earlier version of the article noted that "The [malfunctioning] blimp may have been a blessing: most delegates were watching it when Crosbie made a wrong turn on his grand entrance."
https://med.academic.ru/dic.nsf/enwiki/717307)
Anyway, what would be the best POD for Crosbie winning? If he could somehow edge out Mulroney (and after all on the third ballot his 29.1% of the ballots was not that far behind Mulroney's 35.8%) then it would be between Joe Clark and Crosbie, and presumably the "anybody but Clark" vote would have been sufficient for a Crosbie victory. Maybe our POD would be to have Crosbie learn French--or at the very least not snap when a reporter made his lack of knowledge of French an issue. (Again to quote Wikipedia on the convention: "Crosbie's campaign hit a major snag, however, when he snapped at a news reporter in Longueuil for raising his unilingualism, saying that he would still be able to understand Quebec issues, as his lack of French was similar to not speaking German or another language.[19] While the incident could not harm Crosbie with Quebec delegates, which were already largely split between committed Clark and Mulroney slates, the outburst was seen as showing delegates who were undecided or supporting minor candidates that Crosbie's unilingualism would be an issue in the federal election and could harm the party's chances of winning...") Of course another POD might be having Mulroney in a fatal accident...
Anyway, suppose Crosbie does win the Leadership. Although he won't do as well in Quebec as Mulroney did, nevertheless I assume he defeats Turner in 1984--the Liberals were very unpopular by that time--but what then? How does his Prime Ministership differ from Mulroney's? I know that like Mulroney he was a strong advocate of free trade, but I am not sure how he would have handled other issues like Meech Lake. Anyway, does he get re-elected in 1988? His handling of the 1979 budget does not seem to argue for his political acumen...