World Cup squad announcement:The forwards/backs split is debatable but the coach is sticking to his guns, writes Gerry Thornley

The arguments will rage as to whether a 16-14, as distinct from 17-13, split was the correct formula, but if nothing else, ultimately Eddie O'Sullivan was always going to be true to his word about this one.

There is undoubtedly a compelling argument - which nothing about the events of Murrayfield last Saturday has dispelled - for opting for 17 forwards. By doing this, O'Sullivan could have accommodated six backrowers and four locks, thereby affording him the luxury of rotating the back five in the opening two starting line-ups if he so wished.

It would also have been playing to Ireland's main source or strength, if accentuating the pressure on one or two of the outside backs. Jamie Heaslip and Keith Gleeson are, in part as a result, the unluckiest to miss out.

One of the back five will have to start every pool game and there is no obvious alternative to, say, David Wallace, at openside.

There are no hard-and-fast rules on this vexed issue. O'Sullivan went for a 17-13 split four years ago, as France, Argentina and Australia have done, though France and Australia have the luxury of nominating an outhalf (Freddy Michalak) and a centre (Matt Giteau) who can cover scrumhalf and so are enabled to nominate only two specialist scrumhalves. The All Blacks and South Africa, favourites and second favourites, have preferred a 16-14 split.

O'Sullivan maintained the necessity of picking three hookers and three scrumhalves had limited his options, and so something else had to give. The risk in picking 13 backs would have been too great, according to the Ireland coach, because "if you pick up a couple of soft-tissue injuries to the extent that a player might miss a week, you're very, very skinny in terms of putting a back line and cover on the pitch. That's my take on it. I know other teams have gone in a different direction but I've always held that view."

The net result is that the squad has a welter of versatile backrowers, containing a number of what are ostensibly blindside flankers - Simon Easterby, Neil Best and Alan Quinlan - along with utility backs, namely Gavin Duffy, Andrew Trimble and Shane Horgan or Tommy Bowe.

Geordan Murphy will cover fullback, wing and third outhalf too, while Paddy Wallace can play outhalf or midfield.

Ironically though, another raft of versatile outside backs - Luke Fitzgerald, Robert Kearney and Kieran Lewis - have lost out to a more specialist winger, Brian Carney. While still completing his belated crash course in the union code, Carney has a presence on the ball, no doubt about it, and a touch of class.

That die looked cast from a while back, but of all of them, the one who might have brought the most unpredictable, gamebreaking X-factor off the bench if Ireland were a score or two down in a crunch endgame would have been Fitzgerald - if only for the fact the All Blacks think tank might not have known what to expect from him.

If David Wallace, whose troublesome calf has been bothering him, is to be rested or, worse, is injured for one of the crunch games, there is no obvious replacement for him.

"Stephen Ferris has played there now although I'd be the first to admit that he has a bit to go as an international openside, but Denis Leamy has played seven very adequately and I suppose as well Simon Easterby has played there," argued O'Sullivan.

"We don't have an out-and-out specialist openside because David Wallace wouldn't fall into that category either. But if you look across the World Cup squads I think we wouldn't be unique in that because I think the dynamics of the game have changed," he added, citing the Scots as another example.

No less than with the backrows, it seems among the backs too size now is everything. For that reason you fervently hope Horgan recovers from his grade-two medial-ligament tear in time, not just because he is such a decent bloke but also because his physical presence would be missed in a World Cup that - judging by the high-octane England-France clash at Twickenham on Saturday - appears increasingly set to be a contest between 30 behemoths across the pitch engaged in a never-ending sequence of earth-shuddering collisions.

Add in Horgan's aerial presence for defensive and offensive crosskicks and restarts, not to mention proven finishing ability, big-match temperament and leadership, and his absence would be a severe blow.

In another sense too, it appears O'Sullivan will alter his strategy of four years ago, when eight of the squad played in all four pool games before the limp quarter-final defeat to France, a game that was over by half-time.

Then, a half-dozen of the squad were glorified passengers, but this time O'Sullivan seems intent on delving into his reserves.

He also hinted yesterday that he might mix established frontliners and understudies for the opening two games against Namibia and Georgia prior to the crunch meetings with France and Argentina rather than play his full hand against the Namibians and then rest them or confine them to bench duty against Georgia.

His reasoning, entirely valid, is based partly on the not-impossible scenario of the top three places coming down to points difference - in other words, how many points are accumulated against Namibia and Georgia.

Overall, it is a stronger squad than four years ago, and undoubtedly it was harder for O'Sullivan and co to pick than that of 2003. But while the "squad" should be good enough to cope with Namibia and Georgia, thereafter it will come down to the "team".