In a first for a major T20 competition, the BBL introduced three major rule changes this year: the Power Surge, the Bash Boost and X-factor replacements. The rules were, in part, the brainchild of the BBL's player acquisition and cricket consultant Trent Woodhill. How have the rules changed the pattern of play in the BBL this season and how successful have they been?

The Power Surge

It was designed to maintain interest throughout the 20 overs by moving the last two overs of the normal six-over Powerplay to the second half of each innings, available for the batting side to take from the start of the 11th over, to create some intrigue in what can often be a period of slower-going between the 11th and the 16th overs. The results would suggest it has worked very well.

Last season the scoring rate for the tournament in the last two overs of the Powerplay was 8.01 with teams losing 58 wickets in total. This season the Surge has yielded 10.23 runs per over and 96 wickets have fallen in total.

Across the season the teams that have batted better in the Surge have done better overall on the table than the sides who have bowled better in that period. The Thunder, Scorchers, Stars, and Sixers were the best batting sides in the Surge, with the Sixers, Scorchers, and Thunder finishing top three on the table. The Scorchers, Stars, Strikers, and Renegades were the best bowling teams in the Surge with three of those teams finishing in the bottom four.

The most interesting element of the Surge is which players have benefitted from it. Whilst the big-hitting Ben Cutting is an unsurprising name as the leading Surge scorer, Jordan Silk, and Jimmy Peirson, better known as middle-order accumulators, have had outstanding seasons thanks to their performances in the Surge overs with the bat.

"My big beef with T20 cricket was that the top three [batsmen] would always win the MVP," Woodhill told ESPNcricinfo. "They would come out and go nuts and then there's this whole lull until the last few overs. I think there's a couple of batters who bat in the top three who have said, we've missed that opportunity to go hard in the fifth and sixth overs but they actually weren't going as hard as they thought.

"Jordan Silk has had an unbelievable summer but it's probably one that he wouldn't have had without the Power Surge. And that's no disrespect, but now it's given him the confidence to be able to do that with five men out as well.

"It gives boundary hitters an opportunity, not just your big powerful six hitters. At the back end of the tournament in the BBL, wickets get tired and sometimes batters need some support to get the ball through the field, let alone over the rope."

The Surge has created some accountability for batting groups as well. At times, teams have made a mess of when to take the Surge and there has been no particular blueprint for success. The Thunder often left the Surge late to maximise Cutting and Daniel Sams. Some teams took the Surge immediately in the 11th over after a huge opening partnership only for it to completely derail the innings, like the Scorchers did against the Sixers.

"I reckon it's almost a wickets lost category," Woodhill said. "If you've lost three or four wickets you must take it in the 11th over. Others like the Thunder, they can afford to go a couple of overs out.

"But I think if you're not sure, you must take it. A few teams have thought we'll leave it and take it the next over and they've lost a wicket and lost that momentum. But that's the beauty of it. You don't want to be that black and white that there's a certain over where teams should take it. It varies for each team which is ideal, and it varies for each list which is even better."

Bowling in the Surge has been a different prospect. Of the 23 bowlers who bowled more than four Surge overs in the season, 12 were able to concede less than 10.23 per over. Only four of those were spinners: Adam Zampa, Imad Wasim, Peter Hatzoglou, and Chris Green. Peter Siddle was the standout bowler taking eight wickets with a stand-out economy rate of 7.36. Jhye Richardson also picked up eight wickets and conceded 8.83 per over. The challenge for the quicks has been bowling with only two men out with a softer ball that doesn't swing or seam like it might inside the first six overs.

"We saw around the wicket into the heels of the batters, which has worked against some batters and others who are really good at picking the ball up have been able to meet that challenge," Woodhill said.

"I like that it's brought about some different tactics in the bowlers. I think you'll see some adjustments from the bowlers, especially the quicks around how they move the ball in that period. We've seen with Jhye Richardson, he's been able to move his body around on the crease, where he releases that ball to challenge the batter, which has been really good."

The Bash Boost

At the start of the tournament, the Bash Boost was considered somewhat of an afterthought with teams and fans looking at the big picture of winning the game rather than chasing the point for leading at the 10-over mark.

In the end, the team with the most Bash Boost points, the Sixers, finished on top, and the team with the second most, the Heat, finished fourth when they had won the same number of games as both the Strikers and the Hurricanes and had an inferior net run-rate.

The final game of the season had the added intrigue with the Stars needing to win both the Bash Boost and the game to qualify for finals and they failed to set an adequate 10-over target. The Strikers also cost themselves a home final after missing a Bash Boost point in a win over the Stars. The Strikers needed 10 runs from 12 balls and were just one down at the time but lost 2 for 7 and failed to get the Boost point. They were forced to rebuild to win the game.

For the Hurricanes, meanwhile, there was one over in particular in which their lack of attention to detail cost them: the 10th over of their game against the Stars on January 4. They had started slowly in a chase of 184, reaching 1 for 56 after nine overs, but needed only eight runs off the 10th to secure the Bash Boost. Instead of taking the bonus-point target on, Dawid Malan and Ben McDermott took four singles off the over to miss out on the point, and ultimately lost the game. They would end up missing finals by one point.

There was no clear statistical trend in terms of score increase or wickets lost in the eighth and ninth over across the season. But one clear pattern emerged this year, which ties in with the Power Surge. Scoring was down significantly in the first four overs of the innings. Teams scored at 7.18 per over in the first four overs this season compared to 7.65 last year. The three teams that went the hardest in the first Powerplay, the Sixers, Thunder, and Scorchers, all benefitted the most.

"I think at times, especially in the first half of the season, the top three batters put too much emphasis on their own wicket rather than on their own strike-rates," Woodhill said. I reckon sometimes No. 3 and 4 got themselves in a little bit rather than chasing a better 10-over total. But these are new rules and that's what happens. It's who figures them out the quickest and the best."

Woodhill was surprised teams weren't more adventurous with using a pinch-hitter in overs 6-10. Nathan Coulter-Nile was tried a couple of times for the Stars and Nathan Ellis for the Hurricanes without success. Woodhill believes the next development in the BBL, to maximise the Bash Boost point, could be the use of pinch-hitters and the development of power-hitting among bowlers.

"I think the Power Surge has been an overwhelming success. I know other leagues are already looking at it. The X-Factor is the one that obviously needs greater discussion and teams need longer to work out how best to utilise it."

Trent Woodhill

"If you're 2 for 57 in the eighth over, you're better off sending someone in to chase the point, whether it's a Jhye Richardson, a Rashid Khan, or even an Andrew Tye," he said.

"Obviously you want to hold someone back for the Power Surge. Where the Thunder were really good, they've got Daniel Sams and Ben Cutting, they've got two Power Surge specialists, both strong boys in getting the ball over the 30-yard circle. So there are tactics that are going to develop over the course of the next few years to cope with the changes.

"Someone like an AJ Tye to me all of a sudden becomes a floater. Because he hits the ball that hard and he gets the ball over that infield. Having only two out would be an advantage for him in a Power Surge but more importantly, leading up to a Bash Boost point he's got the power to get it over the five on the rope as well."

One concern with the Bash Boost point is the value of it for a team that loses heavily. The Renegades pinched a point in a 96-run defeat to the Scorchers. The Bash Boost also played a part in making some games extraordinarily one-sided when teams recklessly chased one point after conceding a big first innings score. This season saw the two largest run-margins in BBL history and three of the top four and it also produced two of the three lowest team totals in BBL history.

The X-Factor

It was arguably the least popular of the three new rules with some teams declaring pre-tournament they would hardly use it. In all, every team used it at least once, although the Scorchers only used when Mitchell Marsh was injured. The Heat were by far the most adventurous with it using it seven times while the Hurricanes used it four times.

The Heat have used it in a couple of different ways. The first was naming Chris Lynn as an X-Factor when he was coming back from a hamstring injury, so he only had to field 10 overs and he made a valuable 30 off 16 to set up a win against the Thunder.

They have also used Morne Morkel consistently to replace Xavier Bartlett after he bowls the first over of the match, giving the Heat five overs of bowling from the one position in the side with one over from a new-ball bowler who can swing it, in Bartlett, and four from a veteran, Morkel, who can hit hard lengths and bowl in the Surge and death overs.

The Hurricanes used a similar tactic of selecting a new-ball bowler, Nick Winter, to bowl the first over of the match before bringing in power-hitter Tim David at the 10-over mark. The Hurricanes were forced to adjust in one game when they batted first and were 0 for 91 against the Sixers, with Peter Handscomb volunteering to be subbed out for David.

"I really loved the way Hobart used it with Nick Winter bowling with the new ball," Woodhill said. "Or Jackson Bird bowling with the new ball. If it's not working, bring in a spinner or utilise your allrounders, the way Hobart have brought in Tim David or Brisbane with James Bazley.

"I think it will grow and there's room to adjust the way it's done as well. There's no guarantee that it will stay in its current state. With three overseas players, we've seen the depth of the competition grow and with the X-factor as well it gives teams a chance to adjust after a toss which I think is important."

Teams were frustrated by the limiting nature of the X-Factor, with a decision only allowed to be made at the 10-over mark of the first innings. It clearly favoured the team that bowled first more so than the team that batted first and both Woodhill and BBL head Alistair Dobson have noted that the rule will likely evolve. But there is a keenness to ensure it doesn't just become something that is used at the innings break so that both teams can play 12 and use their best 11 batsmen when batting and simply add an extra bowler when bowling and vice versa.

The Verdict

The Power Surge was a clear success with positive reviews from coaches, players, broadcasters, and fans. It could fundamentally change the way T20s are played if it is adopted more widely. The Bash Boost and X-Factor in their current forms will certainly be reviewed by the League ahead of future tournaments.

"I think the Power Surge has been an overwhelming success," Woodhill said. "I know other leagues are already looking at it. The X-Factor is the one that obviously needs greater discussion and teams need longer to work out how best to utilise it, and then the Bash Boost point, that little peak there where teams have got in that ninth or tenth over where that strike-rate has dipped. That's the challenge to increase that and if it means sacrificing some players around their batting, I reckon that's what is needed."

With inputs from Matt Roller, Gaurav Sundararaman and Shiva Jayaraman