My top 3 would Mulligan, Pickering & Kitchin with an honourable mention for David Baildon. If he'd played in one of Walshy's teams, he'd have been unstoppable.
Bottom 3 is hard. Lots of players have been a bit out of their depth but, as someone else pointed out, it needs a bit of context. so in relation to expectation, tony Smith, Scott Brown and Butch Fatnowna.
Baildon was class in not the best side. While Greg Brake????? Although not is same league, tried his best in poor side, going back to Bamford/Turley era??? Sure h&a will put me right.