Hall of Fame Member
Astle was bowling in a situation where England were just looking to bat out the day - it's a much easier situation for an attacking spinner when the captain can keep the same attacking fields and the batsmen will keep dead batting your full tosses to short cover all day long.Batting balance for 8 and more wicket taking opportunities than Santner is my bet.
Astle troubled England when finally given a bowl, Sodhi still didn't despite his batting heroics.
Craig will always get drift when he cuts the ball as that puts more rpm on it, but it is overspin that he lacks that leads to variable bounce (overspin makes the ball drop faster and more forcefully in flight trajectory), as well as drift. That is what makes Lyon so much more of an off spinner than Craig.
Any pie chucker can roll their arm over and cut the ball and watch it drift and turn big when the pitch is biting. But that overspin movement is far more difficult to master, especially without chucking.
Not to devalue the way Astle bowled, but just saying I'm not sure you can read too much into it vis a vis his relative merits compared to Ish.