Continuity matters - the maturing of the Big Bash

In 1967, a group of 15 men from Glasgow landed in Lisbon to play a game of football. All but one of the squad were born within ten miles of Celtic's ground. Together, they won the European Cup.

Half a century on, the team are an emblem for a lost age in which elite sports teams often were genuinely representative of their local communities. And yet one lesson of the Lisbon Lions endures: the value of cohesion in sport.

The Big Bash League is not really one sports league at all. Instead it is two, of four teams each - those who are the sole team in a city, and those who are one of two. In this season's BBL, the single city teams - Adelaide Strikers, Hobart Hurricanes, Brisbane Heat and Perth Scorchers, the defending champions - have now won ten of their 13 games against the four teams from Melbourne and Sydney.

It is the continuation of one of the most significant statistical trends in the BBL: that single city teams start far better than those from cities with two teams. Over the first six seasons of the BBL, single city teams won 60% of their games against those from two-team cities in the first half of the competition. But in the second half of the season, single city teams won only 45% of games against two-team cities.

The discrepancy speaks of how, in a league with strict salary cap and limits of overseas players, those with more settled playing groups initially have a distinct advantage over teams who have just been banded together. In T20, the notion of team cohesion is not a romantic illusion; what players call 'role clarity' provides a statistically significant advantage in winning cricket matches.

Before last year's Big Bash League, the Melbourne Stars asked Gain Line Analytics, a sports analytics company, to conduct research on the league. Gain Line found that success in the BBL correlated with team cohesion. Teams who had less player turnover - both from their state first-class teams to their BBL sides and year-on-year in their BBL squads - performed most strongly.

And so as T20 leagues enter a new and more mature age, achieving continuity looms as one of the next frontiers on the field.

Gain Line found that the value of continuity extends well beyond the BBL. It can also be seen in Premier League football, where Tottenham Hotspur, with unusual player and coaching continuity, got more points than anyone else between 2015 and 2017 despite having the sixth biggest wage spend in the league.

Gain Line's research has highlighted the importance of accumulated continuity - the cohesion of the team, which is acquired from players working together and knowing each other - in helping a side over-perform their talent, showing how even elite performers tend to need years to replicate their form shown at their old club. What Gain Line term the Team Work Index shows that, when levels of talent are equal, sides with less player turnover tend to be more successful and more durable under pressure.

No BBL side has shown the virtues of continuity better than the Perth Scorchers, who have won three of the last four titles with an almost identical playing and coaching staff to Western Australia in first-class and 50-over cricket. Yet their model relies on being the only team in the city, and is helped by Western Australia's geographical isolation - which renders it far less attractive for players to uproot for two seasons than, say, moving between Melbourne and Sydney - as well as the links between the BBL team and state side. As such, there may be limits in how much this model can be transported, in Australia or beyond.

But cohesion can come in different ways. The Melbourne Stars - the competition's most successful side from a two-team city - provide one example. While other teams have tinkered endlessly with their overseas players, like indecisive children vacillating over their choice of ice cream, the Stars have consciously embraced stability in their overseas recruits.

Uniquely, Luke Wright has been the Stars' overseas player in all seven seasons; for the last four years Kevin Pietersen has been with him too. The Stars have also had unusual continuity in the make-up of their squad: Ben Dunk was their only recruit this season. Still, this stability has not precluded the Stars from repeatedly starting the BBL abjectly - perhaps not helped by Pietersen always flying home to spend Christmas with his family, which has forced other players to shuffle around. After their thumping by Brendon McCullum and Chris Lynn, Melbourne Stars have now won just two of their opening three fixtures across the last five BBL seasons, though they have recovered to reach the semi-finals on all previous occasions.

Brisbane Heat have shown another way to cultivate continuity: prioritising the captain-coach relationship. Both coach Daniel Vettori and captain Brendon McCullum, who are former New Zealand teammates, are in their third season for the Heat, and have signed contracts until the end of the 2019-20 season, which will be their fifth year working together in Brisbane. They have also taken their relationship to Middlesex in England's T20 Blast - though McCullum left midway through for the Caribbean Premier League, which emphasises how difficult it is to develop a captain-coach synergy across T20 leagues and continents.

Perhaps the best hope of developing meaningful continuity across leagues is the Knight Riders model. The Kolkata Knight Riders have bought two teams in different leagues: the Trinbago Knight Riders in the CPL, and the Cape Town Knight Riders in the still-born T20 Global League in South Africa. Coaching and analysis staff are shared across the different teams, opening up the possibility that successful tactics, training methods and general learnings from one league can be imported into another.

While their IPL rivals only have one season a year, the Knight Riders will effectively have three, accelerating their opportunities to innovate and educate themselves in T20. They can also - like the City Football Group, the umbrella company who own Manchester City and affiliated teams in Melbourne, New York, Yokohama and beyond - build a global database of players to help their recruitment to the individual sides.

Yet, if it is to thrive, ultimately the Knight Riders model requires players to be involved in multiple Knight Riders teams. Last year only two - Sunil Narine and Darren Bravo - played for the Knight Riders teams in both India and the Caribbean. It is impossible for the Knight Riders to contract players across multiple leagues because each league has a distinct system for allocating players. In any case, Indian players are barred from playing in foreign leagues. While those two obstacles remain, the Knight Riders model is unlikely to do more than hint at the on-field possibilities of crossovers between teams in different leagues.

That leaves T20 franchises trying to build continuity in less perfect ways. For all the impossibility of mimicking the Lisbon Lions' team dynamics, T20 sides increasingly recognise that cohesion in T20 is worth much more than just another marginal gain.