Because league tables are nonsense.
Both Oxford and Cambridge don't have a score for "Spend per student/10" but in reality both would be 10/10 (they both easily spend much more on each student than any other university thanks to the tutorial/supervision system). You know the league table is a load of rubbish when you see Bristol ranked 24th, when in reality it has the 5th/6th best mathematics course in the UK (I mean seriously, they've somehow managed to rank Birmingham, Exeter, Portsmouth, Heriot-Watt, Lancaster, Swansea, Surrey, Leicester, Oxford Brookes, Leeds, Coventry, QMUL, Stirling Hallam and Southampton all above Bristol?!?)
Funnily enough, their league table is significantly more accurate if you get rid of their own nonsense metric and purely rank by the average entry tariff.