Adil Rashid is probably the best attacking spinner we've got, but are we really after an attacking spinner? It's no secret the strength of the bowling is seam/swing. Therefore in home conditions we can get away with a dud spinner like Moeen Ali. But if we have serious ambitions of being a long time ranked number 1 side, we need a front line spinner.
Whilst Moeen Ali takes the odd wicket, he seldom earns wickets. More often than not it's batsmen error. Therefore using the laws of diminishing returns, Moeen Ali's 'luck' will eventually run dry...