The People's Forum: It's 3x3x3x3x3 - each of five matches has 3 possible outcomes

If it was just two games:
H/H, H/A, H/D
A/H, A/A, A/D
D/H, D/A, D/D
9 combinations

A third game has the same three possible outcomes (yes, really!) which when combined with each of the previous 9 combinations gives:
H/H/H, H/H/A, H/H/D
H/A/H, H/A/A, H/A/D
H/D/H, H/D/A, H/D/D
A/H/H, A/H/A, A/H/D
A/A/H, A/A/A, A/A/D
A/D/H, A/D/A, A/D/D
D/H/H, D/H/A, D/H/D
D/A/H, D/A/A, D/A/D
D/D/H, D/D/A, D/D/D
AKA 3x3x3 combinations of outcomes

And for four games, it's 3x3x3x3
And for five games, it's 3x3x3x3x3

Previous Message

...and I'm not bad at maths, but where does the 243 come from? Is it basically all the permutations that would make a difference in terms of win, draw, loss, goals scored, goal difference etc. etc.?

Unsurprisingly the 16/243 didn't reassure me one jot by the way!