British and Irish Lions 2013: Analysis - The huge risks of calling time on true great Brian O'Driscoll

Brian O'Driscoll, the nearest thing to a "great" rugby player produced by the British Isles in recent times, might well have been the captain of the 2013 Lions and could just as easily have spent the last few days celebrating a first series victory in four attempts stretching back a dozen years. Instead, he is out on his ear, rendered irrelevant by a single flick of a selector's pen. This weekend's drama in Sydney will be staged without him.

In one sense, the decision of the tourists' head coach, Warren Gatland, to drop the 34-year-old Dubliner like a stone – the finest outside centre of his generation does not merit so much as a seat on the bench – was a simple act of preference for one midfield set-up over another: the omission of a player out of form in favour of a second, Jonathan Davies of Wales, who has been playing a whole lot better.

When Jamie Roberts, the only specialist No 12 in the party, was declared fit and fast-tracked into the starting line-up, the two No 13s knew that one of them would be history. Davies would have felt very hard done by had he been the one to feel the sharp end of Gatland's elbow.

Yet in another sense, the cutting of O'Driscoll is one of the more sensational selectorial acts in living Lions memory – far more startling, it is reasonable to argue, than the axing of the England captain Will Carling during the Test series in New Zealand two decades ago. The Irishman has given the very best of himself to the Lions cause. He has scored for them, starred for them, led them, fought tooth and nail for them and broken himself on their behalf. He will go down in red-shirted annals as one of the Chosen Few and he was prepared to give every last remaining drop of his sporting lifeblood to beat Australia in this game.

His fate had something of the Death of a Salesman about it. "You can't eat the orange and throw the peel away – a man is not a piece of fruit." So said Willy Loman, the principal character in Arthur Miller's spellbinding play, and as the news sank in that O'Driscoll had been jettisoned for the first time in his rugby life, there were those who felt Gatland had treated him in precisely that way.

Gatland, the coach responsible for awarding O'Driscoll his first Ireland cap in 1999, was the very last person to underestimate the potential ramifications of his decision, but he argued his case convincingly while portraying himself as the very opposite of a flint-hearted boss. "Once you decide you're going to make the call with your head and not your heart, you take it on from there," said the New Zealander, whose chances of vindication rest with a side showing seven changes from the one that lost by a point in Melbourne last weekend.

"There's a lot of perception out there and this will be a big story for 48 hours, but I'd hate to think I've made calls based on avoiding criticism," Gatland continued. "When I go back to the United Kingdom and I ask myself whether I made this decision because it was right or because it was right politically, I'll be able to put my hand on my heart and say it was because I felt it was the right rugby call.

"I spoke to Brian in advance of the announcement – we don't speak to everyone, but we spoke to him – and he appreciated it. He's very, very disappointed, as you would expect: he's been a big part of the Lions story. But there's a learning process here. When you've been the No 1 in your position for so long, when you've been first choice for everyone, it's hard to go through something like this. There again, it's also been hard for all those people who have seen Brian O'Driscoll selected ahead of them. It's sport."

True enough. But sport is about leadership as much as anything and in making this move under these circumstances – the Lions are not only shorn of the tour captain, Sam Warburton, but are also missing Paul O'Connell, the 2009 skipper – Gatland is risking a good deal of his capital as a selector. He insisted time and again that a good coach picks his team first and his captain second. More chillingly, he also ventured to suggest that this whole captaincy lark is overrated, thereby sounding like the former England manager Martin Johnson. And we all know what happened to him.

In defending his retention of the excellent Davies, the coach fastened on the energy the Scarlets centre showed during the handsome victory over New South Wales Waratahs the week before the start of the Test series – "One of the best performances I've seen from anyone on this tour," Gatland said – and indicated that a shift back to his preferred position in the No 13 channel would give the Lions the best chance of resurrecting an attacking game that died on its feet in Melbourne.

If O'Driscoll had an inkling that this might happen – his public performance on Sunday, less than 24 hours after the second Test reverse, was downbeat in the extreme, and it was only the loss of Warburton to injury that convinced most observers he would hold his place on the grounds of seniority – most of the other changes were more clearly signposted.

Roberts' summons was squarely in the "no-brainer" category, as was the decision to pick Mike Phillips ahead of the overmatched Ben Youngs at half-back and restore Alex Corbisiero to the loose-head side of the scrum once the England prop shook off a calf problem and resumed training on Monday. Toby Faletau's call-up at No 8 was also an obvious move, especially as the Lions are desperate to increase the heat on the Wallabies at the tackle area in an effort to cramp the style of the wondrous Will Genia. And anyway, the Irish No 8 Jamie Heaslip has been a shadow of the player he was in South Africa four years ago.

Richard Hibbard's promotion above Tom Youngs at hooker is as much about the latter's exhaustion after two high-octane Test performances as the former's bulk, while Sean O'Brien's inclusion for the stricken and sadly missed Warburton indicates that the Lions will depend heavily on muscle in Sydney. Had they been interested in putting some pace and width on the game, Justin Tipuric's instincts as a ball-winning breakaway would have been more in demand.

Amid the kerfuffle over O'Driscoll and the predictability elsewhere, there was one genuine mystery. The Lions lost in Melbourne partly because their line-out was a long way short of perfect: the ball they won was of limited use; the ball they lost was damaging in the extreme, not least at the back end of the contest when they had the Wallabies on the ropes.

All things considered, then, the return of Tom Croft, by some distance the outstanding line-out forward in the squad, was well worthy of consideration. Strangely, he did not get so much as a look-in – to the extent that he is not even among the replacements. When the Leicester flanker watches from the stand on Saturday, he will find himself in company of the highest class.

Wounded pride: O'Driscoll's Lions history

2001 Scores four tries in first four matches of debut Lions tour in Australia, but is part of team that loses final Test and series in Sydney.

2005 Captains Lions to first ever defeat against New Zealand Maori before tour ends early after spear tackle early in the first Test results in a dislocated shoulder.

2009 Suffers concussion in second Test against South Africa in Pretoria, forcing him to miss the dead rubber of a third Test.

2013 After becoming only the third player to play on four Lions tours, O'Driscoll is part of side that loses second Test to Australia by one point before being dropped for Saturday's deciding match.