it is not just my word. I have had the good fortune to chat up to some cricketers, including Gilchrist, and they think that with a seamer, since the movement is predictable to a great degree, standing up is not such a tough thing, especially with all the protective equipment available. With a spinner, no one is sure how much the ball will turn, not even the bowler. For instance, Shane Warne knows he put in a lot more work to a certain ball so that it will turn more. But even he will not know how much the ball will turn, even to an estimate. That is why keeping to spin, IMO, is tougher. Our spinners aren't the most accurate going around, and it is so tough to keep to them and not give away byes. They don't have any variety, really, but they are so inaccurate that it is a pain to keep to them sometimes. I can only guess how much tougher it would be at the international level, especially since with sweeps and reverse sweeps abound, keepers easily get unsighted.