This is something I have wondered, especially when Celtic didn't pay that much more than we offered, although he didn't go until the summer when Groeningen had avoided relegation.
There were quite a few games where the manager just sat there. In fact he only really got animated when the referee made appalling decisions, and he got fined for those. He said himself, in an interview, he was fed up with paying out £15K to the FA.
I agree with the majority of your post but I still don't see how Gus's 'ineffective' input caused Hammond to head straight at the keeper, or Barnes to have a shot tipped over the bar, or Moxey to clear another Barnes shot off the line. The actual games were down to the players rather than the...