Paterson and Aitken also "merit" mentions, but so does Porterfield.
Although when Fergie left us in Nov 86 we were languishing below our usual place, Porterfield totally misunderstood what was required at Pittodrie.
Two good things he did:
Got youngsters like Stevie Gray, Brian Grant and Davie Robertson involved in the first team regularly.
Signed Peter and Charlie Nicholas (although it's debatable how much influence he had on Charlie's move)
The bad things:
Thought all he had to do to win was rely on Leighton, McKimmie, McLeish and Miller.
Horrendous mis-use and under-use of Peter Weir.
Believing that some no mark from Shrewsbury Town was a better option than the previously mentioned Weir who had only a couple of years prior ripped to pieces the best full backs in the world.
Playing Willie Falconer. A lot. In loads of different positions. A lot.
With Frank McDougall being injured, he bought Keith Edwards. A shit footballer who didn't score goals. The exact opposite of Frank McDougall, funnily enough.
Not allowing any of Miller, McKimmie or Robertson to cross the half way line, when they were often our best or only avenues of attacking invention.
Bobby Connor anywhere other than left midfield.
Tom Jones.