Similar to Chuck Knox too as Knox had to play Dallas on the road in the playoffs in 1973 after having a superior record and beating them in the regular season as he rotated home field in post season back then.
As to George Allen, well, I agree there was some hard luck, but in 1978 the Rams brought George Allen back because he knew how to beat Dallas and IMO, Dallas was not the problem back then as Knox could not beat the Vikings, which Allen wasn't very good at either. Anyway, although I agree both Allen & Knox suffered from some back luck especially Knox in Buffalo & Seattle too.