Head to head visualisation

Looking at the image below, I want to create the visualisation from the right, based ont he data to the left.

The data is in a table called Results, where (among other fields) I am recording the date of a tournament, each player that played and the result (I also record in the result column if someobody started late by adding "(L)" to the end of it, so when looking at this column it's the left 3 characters that will need to be evaluated.

From this table we can see who was the winner and who was the runner up for a given tournament. I want to turn this into a visual as per the right of the image where we get to see a head-to-head record - that is how much each player has beaten the other player.

So from the data below Dave and Stephen have been first and second 4 times - on 3 occasions Dave won, on 1 occasion Stephen won - so that translates onto the visual as "3 / 1". That reads that Dave (in the row) has won 3 times / lost once against Stephen (in the column). What is below the grey diagonal line is effectively a reflection of what's above it and always would be.

I'd also like the 0's to be displayed instead of blanks in relevant scenarios.

The backslashes were part of my Excel formula in a concatenation - I'd like something to separate the two figures (e.g. separate the 3 from the 1).

I'm not sure how to achieve this in Power BI - any help would be much appreciated.