Over the last few years, most teams have been struggling to put together a stable opening combination. Australia have been the exception, with Chris Rogers and David Warner holding firm and contributing through thick and thin. That was the one aspect of Australia's batting that didn't attract criticism through the failed Ashes campaign in England, with their opening partnerships far outdoing that of the home team. However, with Rogers having announced his retirement after that series, Australia no longer have a stable pair either.

For most of the other teams, finding a consistent opening pair has been among the biggest issues. England won the Ashes despite Adam Lyth's feeble performances as opener, South Africa are searching for replacements for Graeme Smith and Alviro Petersen, India are not sure if Shikhar Dhawan is a reliable partner for M Vijay outside the subcontinent, New Zealand's Martin Guptill and Hamish Rutherford have both disappointed in recent Tests, Pakistan can't quite decide if Mohammad Hafeez fits in at the top, while Sri Lanka are hoping that Dimuth Karunaratne and Kaushal Silva are the answers to their top-order problems.

India had a peculiar problem in Sri Lanka recently, in that even though three of their openers got hundreds - their first such instance in a series - and the combined batting average for their openers was a healthy 46.81, their average opening partnership was an abysmal 5.83. In six innings they managed a total of 35 partnership runs, their worst in a series with a six-innings cut-off.

Overall, these have been rough times for opening pairs. Since the beginning of 2011, the average opening partnership in all Tests has dropped to 35.06, which is a 15% fall from the average between 2006 and 2010. In the same comparison across all wickets - and not just the first - the drop in average partnership is only around 5% (from 35.60 between 2006 to 2010, to 33.67 since the start of 2011), which indicates this fall isn't just the result of overall lowering of batting averages.

The average partnerships have gone back to the levels that were prevalent in the 1990s, when most teams had strong new-ball attacks, from Allan Donald-Shaun Pollock to Wasim Akram-Waqar Younis to Curtly Ambrose-Courtney Walsh to Craig McDermott and Glenn McGrath. The frequency of century stands has reduced too, from one every ten innings between 2001 and 2005, to one every 14 innings in the last five years.

Opening partnerships and openers since 1991 Period Inns Ave stand 100 p'ships Inngs/100 Openers' ave 2011-2015 723 35.06 51 14.2 35.03 2006-2010 765 41.12 69 11.1 37.93 2001-2005 922 41.56 93 9.9 38.82 1996-2000 747 33.23 49 15.2 32.94 1991-1995 580 37.84 50 11.6 35.57

Of the ten opening combinations that have batted together at least 20 times in the last five years, only two of them - Rogers-Warner and Vijay-Dhawan - have averaged more than 50 runs per partnership. The Rogers-Warner pair has consistently got Australia off to fine starts both home and away, putting together nine centuries in 41 innings, including seven from 23 partnerships in away Tests. That includes four century stands in England, two in South Africa and one in Dubai. In fact, they averaged more in away Tests (55.36) than at home (46.38). Clearly, Rogers' retirement will be a huge blow for Australia, not just in terms of the number of runs he scored himself, but in terms of those scored by the team while he was batting.

On the other hand, the Vijay-Dhawan combination has scored most of their partnership runs in two huge double-century stands - 289 against Australia in Mohali in 2013, and 283 against Bangladesh in Fatullah in 2015 - but little else in between. Excluding those two stands, their average partnership drops from 50.20 to 28.77. Unlike Rogers-Warner, who have seven century stands in 23 overseas partnerships, Vijay-Dhawan have one from 21 away innings, and even that was in Bangladesh. Outside the subcontinent, they have averaged 25.70 runs per partnership. Vijay has been terrific with his technique and temperament, but Dhawan's frailty outside off has been a weakness that opposition bowlers have ruthlessly exploited. The overall numbers look good for them, but a little exploring reveals major cracks.

M Vijay and Shikhar Dhawan step on to the field Getty Images

Apart from Warner and Ed Cowan, who average 44.85, all the other pairs in the list below average less than 40, including Alastair Cook and Andrew Strauss, who, during this period, averaged only 33 from 31 partnerships. The pair that looks promising for England was Cook and Nick Compton - they averaged 57.93 from 17 partnerships - but it does appear that England aren't even considering Compton anymore, despite Lyth's Ashes failure. Sri Lanka's Karunaratne and Silva had a consistent 2014 and averaged 45 after 20 partnerships, but a poor series against India has pulled the average back to 36.61 in 26 partnerships. However, with the Sri Lankan middle order in a rebuilding phase, it's likely that the selectors will stick with this opening pair, given that they showed plenty of encouraging signs in 2014.

In terms of team-wise stats too, Australia's numbers stand out. They are the only team with an average opening partnership of more than 40, largely thanks to Rogers and Warner.

Opening pairs since Jan 2011 (Min 20 inngs) Partners Inns Runs Ave stand 100 p'ships Chris Rogers, David Warner 41 2053 51.32 9 Shikhar Dhawan, Murali Vijay 24 1205 50.20 2 Ed Cowan, David Warner 28 1256 44.85 3 Alvirio Petersen, Graeme Smith 38 1354 37.61 4 Dimuth Karunaratne, Kaushal Silva 26 952 36.61 2 Mohammad Hafeez, Taufeeq Umar 31 1018 35.10 3 Gautam Gambhir, Virender Sehwag 26 907 34.88 1 Alastair Cook, Andrew Strauss 31 1033 33.32 2 Peter Fulton, Hamish Rutherford 21 697 33.19 1 Martin Guptill, Brendon McCullum 21 605 28.80 2

Team-wise stats for opening stands in Tests since Jan 2011 Team Inns Runs Ave stand 100 p'ships Australia 97 4391 45.73 14 South Africa 60 2252 39.50 5 Bangladesh 48 1663 35.38 2 England 99 3408 34.77 7 India 81 2708 33.43 4 Sri Lanka 86 2748 33.10 3 Pakistan 74 2329 32.80 6 West Indies 77 2360 31.89 5 New Zealand 73 2321 31.79 4 Zimbabwe 28 643 22.96 1

Between 2006 and 2010, out of eight opening pairs who batted together 20 or more times, seven had average partnerships of more than 40, including two who averaged more than 60. A couple of pairs are in both tables, but achieved far more success during the 2006-2010 period. India's Gautam Gambhir and Virender Sehwag averaged 62.57 from 42 innings, and were particularly successful in Asia, averaging 65.54 in 35 partnerships. From 2011, when India played overseas more often, the pair struggled, averaging 15.16 from 12 stands overseas, though they continued to flourish at home, averaging 51.78 in 14 partnerships. The other pair which features on both tables is the Cook-Strauss combination; their average drops by about ten runs in the period after 2011.

The team stats show that four teams had averaging opening partnerships of more than 40, compared to just one since 2011. The period between 2001 and 2010 was clearly a prolific one for opening pairs. Now, the bowlers are hitting back.

Opening pairs between Jan 2006 and Dec 2010 (Min 20 inngs) Partners Inns Runs Ave stand 100 p'ships Neil McKenzie, Graeme Smith 27 1664 66.56 5 Gautam Gambhir, Virender Sehwag 42 2503 62.57 8 Simon Katich, Shane Watson 28 1523 54.39 3 Daren Ganga, Chris Gayle 28 1197 44.33 3 Alastair Cook, Andrew Strauss 86 3678 43.78 10 Imrul Kayes, Tamim Iqbal 26 1053 40.50 2 Wasim Jaffer, Virender Sehwag 24 962 40.08 3 Imran Farhat, Salman Butt 22 842 38.27 3