A weakness of character, Ian Chappell once said memorably, is like a weakness around off stump. Turn the words around and you get one of the age-old maxims of cricket: poking around the off stump does your batting average no good. But that said, being caught off the outside edge is the most common dismissal in cricket, and even the most virtuous batsmen can't help nicking it every now and then.
Weakness against the short ball is another story. Chappell perhaps never saw it that way, because the short ball was milk and honey to him. Hooking and pulling have been among the great Australian cricket traditions. Footage and photographs of an unhelmeted Chappell - collar up, shirt unbuttoned, and moustache like a horseshoe - swatting away bouncers can still give you a rush. Three Australian batsmen lobbing tame catches off short balls on the first day of the Ashes in Brisbane wouldn't have been a pretty sight for him.
It was certainly not in the script for Australia. After being caught out on uncharacteristically dusty and dry pitches in England, Australia were meant to hustle their opponents on familiar terrain - which they have done spectacularly in their first go with the ball - and three batsmen being dismissed to short balls, it can be argued, is no different from three men being bowled or caught behind.
But Michael Clarke's dismissal was the story. It was certainly a sight. Head turned away, gloves rising to protect it, and the ball lobbing up to the man in attendance. England knew, Clarke knew, the whole ground and everyone watching on television knew, that it had been coming. And when it did, Clarke found himself paralysed, footwork non-existent, no commitment to playing or leaving, and at the moment of impact, just an instinctive and reflexive act to defend his body.
Stumps splayed in the ground might look a more comprehensive mode of dismissal, but helpless jabbing at a bouncer aimed at the body looks like total surrender. It is the worst way for a top-order batsman to get out because a big part of sport's impact is psychological, and a batsman dismissed trying to save his skin and not his wicket not only appears timid, it must feel so to the batsman himself.
But that's not the main reason why a weakness against the short ball is far more serious than some other weaknesses. It's because of the effect it can have on a player's overall game. An international batsman once told me how the dread of the short ball messed up every aspect of his batting. "It's not like leaving the ball outside the off stump. You will yourself to not be drawn into it. It's not simple, but it's about discipline. But there is no getting away from a ball aimed at your body. If you can't play it properly, it gets you in a hopeless position." And most of all, he said, it makes you bat out of character. Just as it happened with Jonathan Trott after he copped one on the gloves from Mitchell Johnson in Brisbane: a fidgety batsman replaced the normally unflappable one, and Trott succumbed to a hurried tickle down the leg side.
There are ways to play a ball aimed at your body. Hit it away with the horizontal bat, find a way to evade it, or ride it with a straight bat and play it down softly. The first and last are traditionally done off the back foot, where the batsman grants himself a fraction of a second more and a bit of space to deal with the ball. Ricky Ponting had exceptional skills and the confidence to be able to pull consistently off the front foot, but it sometimes got him into a tangle when his reflexes slowed with age.
*And there is another way. Guts and courage. Being prepared to take blows on the body. Brian Close, pushing 45, took it to the level of absurdity by taking a battering at the hands of the West Indian quicks in 1976. The modern player is, of course, better protected, but Steve Waugh and Justin Langer come to mind as players who valued their wickets above bodily hurt, and MS Dhoni in his early years fronted up to bouncers with a puffed-up chest, as if to ask the bowler: that's all you've got?
Front-footedness is the contemporary way. It's the best way to score runs on batsman-friendly pitches, and to cut down the swing against the new ball. The modern batsman is a creature of the times. Pitches have gone slower, hitting through the line with modern bats has become more rewarding, and genuine quick bowlers have been rare. Clarke's footwork down the wicket is twinkling, and when at the top of his game, he drives sensationally, but unlike Australian greats from the past, his back-foot game against quick bowling is underdeveloped.
His major scoring shot against the short ball has traditionally been a swivel-pat, where the bat gives direction to the ball rather than lashes it, but that stroke comes up only after he has a few runs under his belt. Perhaps his persistent back problems have further restricted his ability to pivot, and they might also have hampered his ability to sway or arch out of harm's way.
Old-timers will detect a degree of irony in the appointment of Graeme Hick as a batting coach by Cricket Australia. His weakness against the short ball was the only thing that kept Hick from attaining the batting greatness that had always seemed destined for him. It was his misfortune that his entire career, 1991 to 2001, coincided with one of the great eras of all-round fast bowling, and he ended up playing 18 of his 65 Tests against the West Indians - starting against Ambrose, Walsh, Marshall and Patterson, and ending while Ambrose and Walsh were still around. Lesser batsmen than Hick have averaged over 50 in the last decade.
Vinod Kambli, who can now boast a better Test batting average than his schoolmate Sachin Tendulkar, had his career put to rest in his final series against West Indies, who targeted him with the short ball, and Suresh Raina may never have the Test career he covets because bowlers around the world now know of his troubles against the short stuff.
Clarke has already built a substantial career, and he remains among the best batsmen in the world, and the fulcrum of Australia's batting. But in the last quarter of his career, he has now found a weakness exaggerated. That the short ball has accounted for him nine times out of the last 18 in the Ashes is not an odd statistic. It points to a struggle that has now become almost as big a challenge as winning back the Ashes.
*08:18:33 GMT, November 22, 2013: Paragraph added
Sambit Bal is editor-in-chief of ESPNcricinfo