It gets even more wonky when the plurality does not support the disposition of the case (i.e. - the single largest block of judges would have done the opposite of what actually happens with respect to appeal allowed or dismissed).
Suppose you’ve got nine judges sitting on an appeal from a conviction, and the appeal raises two issues: does the Court have jurisidiction to hear the case? and should the evidence in question have been admitted?
Let’s further suppose that four of the judges are satisfied that the Court has jurisdiction, and then conclude that the evidence should not have been admitted, so they would allow the appeal.
However, three of the judges think that the Court doesn’t have jurisdiction to allow the appeal. They therefore would dismiss the appeal. Being minimalists, they conclude that since the Court doesn’t have to decide the question of the admissibility of the evidence, they won’t deal with that issue. In their reasons, they state that they are intentionally not dealing with the evidential issue.
The remaining two judges think the law is clear that the evidence was proprerly admitted, but they think the jurisdictional issue is complex and should be left to another day. Since ruling on the evidence issue is sufficient for them to dismiss the case, they say, “Assuming the Court has jurisdiction (but not deciding it at this time), the evidence was properly admitted” and they would dismiss the appeal.
So the result is 5-4 in favour of dismissing the appeal. Of the majority in favour of dismissal, three dismiss for want of jurisdiction, two because the evidence was properly admitted. The plurality on the reasons is in the dissent on the result, since those four judges would have allowed the appeal.
Nor is there a clear majority on either the jurisdictional issue (4 thought there was jurisdiction, 3 did not - and the three are in the majority on the result, the four are dissenting on the result), or on the evidence issue (4 would have ruled it inadmissible, 2 admitted, and the 2 are in the majority on the result, and the 4 are in the dissent on the result).
And this hypothetical assumes that the plurality hangs together, with the same four judges voting the same way on both issues. When they don’t do that, with shifting views on each of the issues, the result can be as described in some of the above summaries.