I don't know if there are stats for unused benchmen.
As for your other questions.....its hard to answer because this phenomena of some players getting zero minutes is relatively new. Cappy did it if IRC.
Certainly it is no one off thing....but I haven't heard any Authority in the modern game shed light on carrying players that might not play at all.....and even opposition coaches have raised an eyebrow in post match Presser's when asked to comment on some of our unique uses of the bench.
I'm glad you mentioned the Seventeen man game Maxim. The use of our bench has seemed to challenge all accepted wisdom and convention.
Roach has sat on the bench, + Tui......and then there was the Cappy /Elliot stuff where we carried an outside back on the bench for some games.
So we are not talking a one off thing.....but it seems peculiar to this club.
My best guess is the experimentation is being guided by overriding principles the kind of process stuff, and before that the Cappy/Elliot KPI focus (a spare back to cover tiring unfit backs....Insurance for Injury prone backs).
I think Kearney
's bench use is an extension of his sticking with the same starting 13....its almost as if he won't risk change.
Basically its a risk adverse approach in the interest of finding consistency.
So you pick experience over form.
You invest in the idea that your most experienced guys are best equipped to follow the process.
As such, you try to make as few changes to staffing. This mentality makes a persona non grata on a bench possible.
Impact from the bench becomes a lesser goal (in a team where players often wander from the script).
Most of all I think our odd bench scenario's are driven by:
1) A lack of experienced alternatives to drive competition for spots/ give the coach options
2) consistency is not being seen at training.
3) our players are shyte defensively In the Under grades making it very hard to run a conventional bench for a regular 13 who are struggling to change their ways under the hundredth fg coaching change.