Big Bash rule changes: 'Power Surge' and 'Bash Boost' — what on earth do they mean and will they work?

One curiosity of the first 17 years of Twenty20 is how a format borne out of experimentation has seen so little experimentation with its rules. For all the tactical evolutions in the sport - the rise of match-ups, the use of spinners at the start of the innings and the unprecedented focus upon six-hitting - the essential rules have been unchanged.

Eleven-a-side, six overs of Powerplay at the start of the innings and four overs per bowler: the rules that matter are exactly as they were when the inaugural T20 Cup game was played at the Ageas Bowl on June 13, 2003. In the same period, one-day international cricket has embraced two balls per innings, changed the fielding restrictions and experimented with multiple Powerplays and substitutes. And supposedly crusty Test cricket has introduced day-night matches - including the pink ball - new decision-making technology and allowed four-day Tests to be scheduled.

The lack of tweaks to the main rules of T20 are a symptom - and perhaps a cause - of why it has established itself as the most popular format of the game worldwide. The format hasn’t needed to experiment because the cricket has been compelling enough, as anyone who saw the recent Indian Premier League would attest.

But while the IPL has surged, the Big Bash has floundered in recent years, suffering from being too long, a diluted talent pool and clashes with Australian internationals. Rather than address these fundamental issues, the Big Bash has now become the first major T20 league to experiment with radical rule changes. This season, which begins on December 10, the Big Bash will introduce the Power Surge, X-Factor and Bash Boost. These are the new rules - and how they will change the sport.

New rule: Power Surge

How it works: Instead of the six-over Powerplay at the start of the innings, there will be a mandatory four-over Powerplay at the start. The remaining two overs can be taken by the batting team at any point from the 11th over of the innings onwards.

What it will mean: The most intriguing - and promising - of the tweaks, the Power Surge will make T20 innings more unpredictable. Aggressive teams will take the Power Surge during the middle overs, using it either to help set batsmen accelerate or using a particular batsman to exploit the Surge. For instance, Sunil Narine, who was used as a middle-over aggressor in the last IPL, would be ideally suited to batting during the Power Surge given his aggression and the relative lack of value to his wicket.

Bowling teams, in turn, will either have to stick with their normal bowlers in this phase, or bring on their death bowlers and leave them fewer goes at the death. Attacking fielding sides will see the Power Surge as a chance to hunt wickets, as Ricky Ponting’s Australia team did in the ODI World Cup in 2007 using Shaun Tait to great effect during the mid-innings Powerplay periods, which were scrapped shortly after. Spinners accustomed to bowling with a spread field will need to adapt.

New rule: X-factor player

How it works: An 'X-factor Player' can come into the game as a substitute after the 10th over of the first innings. He can replace any player who is yet to bat, or has bowled no more than one over.

What it will mean: Strongly resembles the old ODI SuperSub rule, which was scrapped after flopping in 2005. The X-factor rule will give teams some insurance if they misread a pitch - for instance, a spinner could replace a seamer on a turning wicket. But reading a pitch is an art: it is unclear why teams should be compensated if they get it wrong. In any case, players not good enough to be in the starting XIs of the eight Big Bash teams, even with many Australian stars unavailable, hardly qualify as X-factor. Less controversially, the X-factor rule will also allow teams to replace injured players. But this rule threatens to go the same way as the SuperSubs.

New rule: Bash Boost

How it works: A bonus point will be awarded halfway through the second innings. The chasing side will receive the bonus point if they're above the equivalent 10-over score of their opposition; if they're trailing, the fielding side will receive the point.

What it will mean: It will create new dynamics in a run chase: teams may bowl their best bowlers more at the start of an innings to secure the bonus point, and risk their chances of winning the game in the process. Conversely, batting sides chasing an outlandish target may throw all their eggs into getting the bonus point by overhauling their opponent’s 10-over score, however many wickets they lose, and even effectively sacrificing all chances of victory. Like the other two rule changes, the Bash Boost will create more decision-making for coaches during games, accelerating one of the great shifts of the T20 age: coaches becoming more important, and more accountable.

Yet the Bash Boost appears an artificial tweak that threatens to decrease the stylistic diversity in T20. Batting sides who are most adept at exploiting the death overs of an innings - think of Trinidad & Tobago in early editions of the Champions League, the West Indies in the last T20 World Cup and Mumbai Indians with Kieron Pollard and Hardik Pandya - will be penalised by this arbitrary rule. With three points for a win and one point for the Bash Boost, the rule will also allow teams with fewer wins to advance to the play-offs over those with more wins, undermining the integrity of the competition.