"It's the CANDIDATES, stupid".
The quality of a candidate matters. In analysing results there has been practically no mention of 'personal' effects. Pundits say the results are all over the place, as though they have given up trying to understand the trends, but meaning of course that some candidates do better than average and some do worse. Some show a 'swing' of + 8%, while the national trend was essentially zero gain; others loose a 'safe' seat. The Lib Dem share of the national vote has inched up over the years: '92=17.8%, '97=17.8%, '01=18.0%, '05=22.1%, '10=23.0%. Once again people seem to miss something. They think this is natural, because it is something that has been happening all their lives, and they have given up trying to discern the causes. But I suspect that one significant meaning is that the quality of candidates has been rising steadily over the decades. Success in one election means more people are prepared to step forward next time, and so the effect builds.
With an Alternative Vote system it will be vital not to be the 'bottom' candidate in any constitiuency'; their votes get lost. A candidate who comes second could however end up as MP when the re-assigned votes are totted.