COMMENT: Chopped, changed, unsettled and injured, Martin O’Neill’s defence is an abundance of riches

Call it experimentation, call it indecision, call it whatever you like, but it is working.

Republic of Ireland manager Martin O'Neill has failed to select the same defence in consecutive games for over a year but it has little impact on performances. The 2-2 draw with Slovakia on Tuesday was only the second time in almost two years and 17 matches that Ireland have conceded more than a single goal in a game. Since being shredded 5-1 by a Portugal side preparing for the World Cup in Brazil, O'Neill's rearguard have held their own against the likes of world champions Germany, Poland and England. Before Tuesday night it had taken an attacking talent of the calibre of Poland's Robert Lewandowski to pierce the defence on multiple occasions in 90 minutes. However the credit for Slovakia's goals at Aviva Stadium are being laid at the feet of Paul McShane, rather than any visiting attacker. The Reading centre-half ill-advisedly lunged in on the halfway line in the run-up to the opener and was slightly unfortunate to deflect the second home as he attempted to cut out a dangerous ball across the six-yard box. The Euro 2012 veteran, starting his first international in almost three years, in effectively playing himself out of the Euro 2012 squad, has helped O'Neill cull numbers in the most competitive area of the field. The knee ligament injury suffered by goalkeeper Stephen Elliot in the concession of the first goal makes another decision for O'Neill, who has been denied the services of the only goalkeeper regularly playing in the Premier League, with Newcastle United. The goalkeeping position is the defensive situation in microcosm. Players, for the most part, of modest club status, giving the Ireland management team little or no reason to abandon them at international level. Elliot's injury is a blow, but he was, at best, second behind West Ham's 'Cup' goalkeeper Darren Randolph, who has made the number one shirt his own since coming on as a substitute in the vital 1-0 win over Germany in October. Just as the Euro 2012 door is slammed on Elliot it opens a crack for the man whose injury gave Randolph an opportunity against the world champions. Shay Given has been sidelined with a knee problem since that famous win but a route back into the Stoke side and the Euro 2012 squad presented itself two days before Elliot's misfortune. England and Stoke netminder Jack Butland's broken ankle could be the long-time Ireland number one's route back to relevance and France, where he is likely to join one of Keiren Westwood and David Forde alongside Randolph. None of the above, who have all seen game time during O'Neill's time in charge, have been over-worked, playing behind a variety of back fours that contains only one player who can be considered "world class". Martin O'Neill has not played the same back five in over a year At least that is the former Leicester City, Celtic, Sunderland and Aston Villa manager's assessment of Everton full-back Seamus Coleman, who captained the side for the 1-0 win over Switzerland. Rested for the draw with Slovakia, Coleman's "under study" (another O'Neill description), Derby County full-back Cyrus Christie did his own prospects no harm with another attacking performance, which is a requirement to give width in O'Neill's preferred narrow, diamond midfield formation. On the other flank Norwich City's converted winger, Robbie Brady naturally gives the necessary attacking width and has been adding the defensive solidity to his game. Given Brady's ability to play in midfield it is likely Burnley's resurgent Stephen Ward will travel as cover, along with Christie and Coleman - leaving 3-4 central defensive spots in the squad O'Neill will name the day after the May 27th friendly with Holland. McShane was the sixth centre-half given a start by O'Neill in the past 12 months and, perhaps, the only one who can be discounted at this stage. If the Slovakia match was an outing to forget for the Irish defence, Friday's 1-0 defeat of Switzerland was a tour de force. With Coleman captaining the side, the back four of the Everton man, Shane Duffy, Ciaran Clark and Brady kept an admittedly meek Swiss side at bay. On top of that the only goal of the game was scored from a second minute penalty by Aston Villa's Clark, who glanced a powerful Duffy header to the net. It was the perfect start to an impressive display from the unique pairing. While Duffy - a big, powerful specimen - has been enjoying a good season with Championship mid-table team Blackburn, Clark has been struggling to get a game for an Aston Villa side destined for England's second tier. Together they formed a very solid partnership and the flat atmosphere at the Aviva on Friday allowed everyone enjoy the sound of 24-year-old Duffy barking orders at his more experienced colleagues on his second appearance. With Sunderland captain John O'Shea nailed on to start in France, the Clark and Duffy show will have turned up the heat under Derby's Richard Keogh and Mark Wilson, who has endured an injury-hit season at Stoke City. Like everyone else in this revolving Irish defence, they have done little wrong when given a opportunity, but those opportunities to impress are running out. If only O'Neill had such viable options in other areas of the pitch.