How good is Sehwag?

As a demoralised, underprepared, injury-ridden and outclassed Indian team attempt to regroup for the third Test, the air of expectation surrounding the return of Virender Sehwag can be compared only to that of the faithful anticipating the second coming.

Despite the facts that he has played little cricket since the World Cup, and that his shoulder has been under the surgeon's knife and has barely had the time to recover, Sehwag is seen as the saviour, the genius whose confident and positive strokeplay will take the fight to the opposition and give India the kind of starts they haven't been able to dream about since he last played.

Whatever happens when he actually does take strike again in Edgbaston, the extent to which he has been missed by India over the last five Tests points to his extraordinary importance to this team. India look like a different side without him at the top of the order.

It also raises the related question of whether he should finally be hailed as one of the game's greats, along with two of his current team-mates, Sachin Tendulkar and Rahul Dravid.

When does a cricketer cross the invisible line that separates the very good from the truly great? There is no simple formula. Cricket is famously a game of statistics, but it can be no one's case that a career batting average above 50 is proof of greatness. If that were enough, the likes of Thilan Samaraweera (54.08) and Ken Barrington (58.67) would have to be mentioned in the same breath as Bradman and Tendulkar, while Clive Lloyd (46.67) and Adam Gilchrist (47.60) would fail to make the cut. Sorry, won't do.

Longevity could be another factor. One brilliant season does not a great batsman make, but someone who displays a sustained level of excellence over many years and many Tests can be argued to have a claim to greatness. And yet - what number of seasons and matches should furnish our yardstick? Five years? Twenty-five Tests? The latter would oblige us to omit George Headley (22 Tests, average 60.83) and Graeme Pollock (23 matches, 60.97), both of whom were considered by their peers to be amongst the immortals. Pollock's Test career was cut short by the international revulsion against the apartheid practised by his country, and some would argue he did not play long enough, or against varied enough opposition (West Indies, for instance) to earn the encomia lavished upon him. But Headley played long enough - 1930 to 1954 - to offer enough proof of his greatness, even if World War Two deprived him of six years when he was at his peak.

How about centuries, long a basic yardstick of batting success? Could, say, 20 hundreds be seen as proof of both ability and longevity, and therefore a statistical measure to complement the average? Certainly the unquestioned greats - Bradman, Sobers, Hammond, Tendulkar, Gavaskar, Lara, Dravid, Kallis - all make the cut. But so do Barrington, who made his runs dourly, with impregnable technique and limited flair, and Graeme Smith, who has excelled in spurts without ever suggesting a smidgen of greatness.

Sehwag passes all these tests - 22 centuries, an average of 53.43 in 10 years at Test level. Yet clearly no statistical measure is sufficient in itself.

What about big hundreds, doubles, even triples? There Bradman steals a march on almost everyone. But Sehwag, with 184 as his average century score, and 14 of his centuries exceeding 150, four double-hundreds, two triples (the only triples ever scored by an Indian batsman in Tests) excels over almost everyone else, barring Lara.

One must, then, inevitably, turn to those factors that don't lend themselves to easy quantification. The circumstances in which a batsman's runs were made, the context of the matches and the quality of opposition, are all difficult to measure and to give due weight to. But clearly runs made against Australia or South Africa in the last decade ought to count for more than centuries taken off Bangladesh or Zimbabwe. If a successful batsman's career shows a disproportionate level of success against modest opposition, the sobriquet of greatness would have to be withheld. If, on the other hand, you've made hundreds against the best bowling attacks in the world, as Sehwag has done against the best that Australia, South Africa (remember his 319?) and Pakistan (his first triple-hundred) could fling at him, you are pretty special.

Similarly the role of a batsman in overpowering the bowling - in demolishing the opposition to an extent that undermines the same bowlers' ability to perform against the other batsmen - is difficult to quantify. Strike rate is now available as an indicator, but it omits the value of a Dravid or a Gavaskar, who prized their wickets, rarely scored at a brisk clip, but were indispensable to their sides precisely for this reason. Yet when all the other statistics are allied to a brisk strike rate, the impact on the opposition can be considerable. It can ensure the batsman's success in laying a platform of dominance for others to build on.

When Kevin Petersen declared in the Chennai Test against India in 2008, he thought 387 was too high a target for India to attain in the time, and the roughly 100 overs available, especially since they had been bowled out for 241 in their first innings. He reckoned without Sehwag, who smashed 83 off 68 balls, with 11 fours and four sixes, at a strike rate of 122.05 - and suddenly made an impossible target seem gettable (which, thanks to a Tendulkar century, it then turned out to be). One indication of Sehwag's greatness is the fear he evokes in the other side, that they are never safe as long as he is playing. It is no accident that two of the three fastest triple-centuries on record (in terms of balls faced) in the history of the game are his. His career strike rate is just a fraction short of No. 1-placed Gilchrist's (with a qualification of 2000 runs).

Sehwag appears indifferent to such figures. He has an uncomplicated approach to batting - if he feels a ball is there to be hit, he hits it, often successfully (having brought up several of his landmarks with a six), and sometimes unsuccessfully (having famously perished going for his shots at 195 and 293, when lesser mortals would have pushed and nudged their way into the record books). But when his team has needed defence, he has demonstrated the ability to provide it: 151 on his comeback to the Test side in 2008 after unfairly being dropped for a year - an innings that saved the Adelaide Test - and 201 not out in Galle the same year, when the rest of the team's batsmen put together could only manage about half as much against the spinning wiles of Mendis and Muralitharan.

In other fields, an accepted measure of greatness is the demonstrated ability to overcome adversity in the pursuit of achievement. Indians tell stories of Gavaskar's 220 in the West Indies despite a crippling toothache, or Kumble bowling with a bandaged jaw. Sehwag's adversity was not a physical trauma, but the emotional injury of being dropped when he was arguably one of the side's most valuable players. Someone else might have changed his style of play to get back into the side. Not Sehwag: he backed himself to prove himself while being himself.

The ultimate test of a batsman's greatness, of course, is the extent of a side's dependence upon him. Sehwag is up there as India's Mr Indispensable, in every respect able to hold his own with Dravid and Tendulkar. ESPNcricinfo's Statsguru confirms that if one were to count just the 73 Test matches in which the trio of Dravid, Sehwag and Tendulkar have all played, though Tendulkar has the highest average in these matches (55.45, Sehwag second with 54.40) and Dravid the most centuries (19, Sehwag joint second with 18), it is Sehwag who tops the tables of runs scored (6583, over 650 more than the other two), with by far more boundaries hit and at (obviously) the fastest strike rate (over 81, to 53 for Tendulkar and 44 for Dravid).

Sehwag has been sorely missed every time he has not figured in an Indian line-up. If he transforms the fortunes of this beleaguered Indian side in the second half of this English summer, he will merely confirm the greatness that many of us have long believed is already his.