I'm not an expert on the guardians tables or it's measures but there are a number of common flaws in these.
1) (as some have mentioned) There is too much emphasis on student satisfaction.
not only is this something that is difficult to define (is it a problem with the teaching or is it just in an awful or expensive town or is there something with career prospects ... or well you get the idea it could be anything)
2) league tables that include 'value added' favor lower uni's
- partly because they have a more nurturing teaching style
- partly because the students give them more to work with compared
to places where students may already have A*A*A* and there's less room to add.
3) Papers and their writers are political and they can bias the stats to favor uni's that they already favor
4) entry points can be inflated by international qualifications which translate into a lot of ucas points. London uni's with equal entry grades to places like bristol and durham will have higher ucas averages because of more internationals
5) it's hard to quantify the quality of professors / teaching
6) positions fluctuate wildly from year to year
7) the stats could give a measure of something... but generally what most students want to know is how valued it will be when they come to look for a job and that's the most important factor to get overlooked!
The only real measure for it they have is starting salaries, which can be pretty non informative about the future of the career
% in jobs is another one... but again.. what jobs.. where...
you won't be able to point out an ephemeral league table position on your entry year on your CV to explain why your employers never heard of it and it's in a massively different position now you see
well that's what i've gathered in all my uni anguish