It's pretty simple - he can only bat when the pitch is dead flat. Put any sort of pace or movement in the wicket and he's just another tail ender. Look at the tons he's scored:
134* n/o vs india - 1273 runs scored in total, match drawn...other centurions - 2 (although there were 4 other scores of 70+)
186 vs pakistan - 1483 runs scored in total, match drawn...other centurions - 4
206 vs aust - 1361 runs scored in total, match lost (should've been a comfortable draw)...other centurions - 3
I realise that the likes of Ponting would've made many a ton on similar pitches...but that's not my point
My point is that Collingwood is yet to produce an innings that has influenced the outcome of the game. Like Bell, he finds his runs most often when the hard yards have been done by the batsmen preceeding him, when the runs are already flowing. Put him in a pressure cooker situation with a new ball that's still nipping around and he gets out cheaply more often than not (Bell has improved somewhat however, but the number of times he plays and misses you'd have to say that's more due to luck than anything).
Like many of his English counterparts there's no flexibility in his batting. He bats the same no matter the state of the game - block, block, block. His 206 in adelaide was the most painful innings I have ever seen. For whatever reason he never took any chances to increase the tempo and left England in a position where the best outcome would've been a draw. I don't know if there's such a thing as a century that can lose you a match...but that is as close as you'd come.
As for gingers - isn't one Shane Warne a ginger???? We all know he bleaches his hair, but i'm pretty sure his eyebrows are ginger...and last season he had a goatie that looked awfully ginger...plus his children are gingers. I think he claims to be a strawberry blonde, but i reckon that's just his excuse when he gets a bit slack with the bleaching.