A team of officials marks over a season - analysis

We have a team of over 30 officials (of which 20 are used each week), they are marked on their weekly performances on a scale of 1 - 10
Each official should have over 6 marks with the majority receiving 12-15 marks in a season.
The marks are awarded by a team captain (who probably is influenced by whether he wins or not or some other influencing factor!)
2 officials per game and each is marked by the 2 captains of the sides in the game.

I am looking as to how to analyse the officials marks and be able to rank them and provide a score to compare them.

Further difficulties stem from the fact that different captains score differently and that the officials may not be scored by all captains and may be marked by one captain more frequently than others. Also a Captains average perhaps should not be swayed by an excessively low mark given for a perceived poor officials performance, so maybe averaging is not suitable.

The majority of the scoring will be in the 6-8 region.

My initial thoughts given the requirements was to find each captains mode mark (his perceived "average" performance) and score each mark given as the difference +ve or -ve to the modal score, thus giving each official a variance for each mark awarded. These would then be added and the sum divided by the number of marks awarded.

Does anyone have have any other suggestions or observations?

This work is completed freely and after work so a complicated methodology is not appropriate.