RUGBY:IRELAND SQUAD announcements have become like maths equations of late. In pruning their squad of 39 to 31, the Ireland management have moved 13 players to the 22-man Irish A squad, called in seven others not in the original panel and ruled out Marcus Horan and the injured Tony Buckley. Yet there is clear method to such musical chairs.

Most of the big calls have been deferred until next Wednesday, when the staring line-ups and replacements to face Australia at Croke Park tomorrow week will be announced.

The most eye-catching call, perhaps, is the demotion of Peter Stringer to the A squad to face the full Tongan side at Ravenhill next Friday, which means Eoin Reddan has jumped ahead of Ireland’s most capped scrumhalf in the pecking order.

This is tough on Stringer, who is thus the only member of the Grand Slam-winning squad to be demoted. But since he started Munster’s opening two games of the season, he has made only three appearances off the bench in their last seven games. By contrast, Reddan has been playing well and started for Leinster in six of their last seven games.

For the most part, Declan Kidney and his coaches have one eye on the 2011 World Cup in their composition of the A squad, although the good form of seasoned internationals Shane Horgan and Andrew Trimble merited inclusion against Tonga.

In the heel of the hunt, the seven players called up to the senior squad – Bob Casey, Mick O’Driscoll, John Muldoon, Niall Ronan, Denis Hurley, Felix Jones and Ian Dowling – have not suddenly overtaken those who have dropped down to the A squad, or indeed others, such as Kevin McLaughlin or Johne Murphy, who have been selected for the Tongan game. All seven were involved in the summer Tests or Churchill Cup.

Hence the decision to play the Churchill Cup final secondrow pair of Donnacha Ryan and Devin Toner against Tonga rather than the likes of Casey and O’Driscoll (who played the preceding Tests against Canada and USA), while the others to be called up to the senior squad are being rewarded for form and are kept on the radar.

Kidney and co also like to have two full sides for training at the start of match weeks, and so a fourth prop is likely to be called in.

Jerry Flannery took a fairly full part in yesterday’s sessions before the squad broke up for the weekend, although the strained hamstring which ruled out Rob Kearney for Leinster’s win over Cardiff last weekend again sidelined him.

The only others not to take part were Denis Leamy, Paddy Wallace and Tomás O’Leary, who were recovering from colds.

Were Flannery to be ruled out next week, the likelihood is Ireland would start with two debutants in the frontrow, namely Cian Healy and either John Fogarty or Seán Cronin. For the moment therefore, three hookers have been retained in the senior squad, with a vacancy in the A squad.

As it is, presuming Flannery and Kearney are fit, it’s conceivable the only change from the starting line-up that completed the Grand Slam against Wales in Cardiff last March will see Healy make his Test debut in place of Horan. The latter’s loss has at least been offset by the upward graph in Healy’s form last season and this.

While the second leg of the autumn series, against Fiji at the RDS, might offer some scope for squad rotation/experimentation – such as promoting much or all of the bench – it’s likely Kidney and co will look to pick their strongest sides for the Australia and South Africa matches. However, there remains a tight call at inside centre, most probably between the men who shared the position in last season’s Six Nations, Gordon D’Arcy and Paddy Wallace.

Thus, next week’s team could read: Healy, Flannery, Hayes, O’Callaghan, O’Connell, Ferris, Wallace, Leamy, O’Leary, O’Gara, Fitzgerald, Wallace, O’Driscoll, Bowe and Kearney. Were Kearney, who is still expected to play, ruled out, then Keith Earls would probably come into the back three, with him or Luke Fitzgerald starting at fullback.

Compared to that grand day in the Millennium Stadium, aside from Reddan replacing Stringer, the bench could see one of the two uncapped hookers, most probably John Fogarty, come in for the absent Rory Best. Leo Cullen now seems to be ahead of Mick O’Driscoll in the secondrow pecking order, the uncapped Jonathan Sexton is emerging as the understudy to O’Gara, and either D’Arcy, Paddy Wallace or Earls will complete the 22 in place of the injured Geordan Murphy.

Tom Court has been preferred to Mike Ross, even though the latter’s scrummaging has been more impressive this season, presumably because he has packed down at both loosehead and tighthead. Leamy will also remain in the 22, at the very least, after his strong showing against Ulster last weekend.

Neil Best may well captain the As, as he did in the Churchill Cup final win over England, on what would be an emotional return to Ravenhill in a squad that could will feature eight of that victorious side as well as seven other Ulster players.

Ian Humphreys is likely to start ahead of Ian Keatley (preferred against Canada and the USA), who have, unsurprisingly, been chosen ahead of the English Premiership’s leading points-scorer Jeremy Staunton, who has accumulated 109 points in nine starts for Leicester Tigers this season.

IRELAND SQUAD (v Australia): T Bowe (Ospreys), B Casey (London Irish), T Court (Ulster), S Cronin (Connacht), L Cullen (Leinster), G D’Arcy (Leinster), I Dowling (Munster), K Earls (Munster), S Ferris (Ulster), L Fitzgerald (Leinster), J Flannery (Munster), J Fogarty (Leinster), J Hayes (Munster), C Healy (Leinster), J Heaslip (Leinster), D Hurley (Munster), F Jones (Munster), R Kearney (Leinster), D Leamy (Munster), J Muldoon (Connacht), D O’Callaghan (Munster), P O’Connell (Munster), M O’Driscoll (Munster), B O’Driscoll (Leinster), R O’Gara (Munster), T O’Leary (Munster), E Reddan (Leinster), N Ronan (Munster), J Sexton (Leinster), D Wallace (Munster), P Wallace (Ulster).

IRELAND A SQUAD (v Tonga): N Best (Northampton), I Boss (Ulster), D Cave (Ulster), G Duffy (Connacht), D Fogarty (Munster), C Henry (Ulster), S Horgan (Leinster), I Humphreys (Ulster), I Keatley (Connacht), F McFadden (Leinster), K McLaughlin (Leinster), J Murphy (Leicester), S O’Brien (Leinster), M Ross (Leinster), D Ryan (Munster), P Stringer (Munster), D Toner (Leinster), A Trimble (Ulster), D Tuohy (Ulster), B Wilkinson (Connacht), B Young (Ulster), AN Other.