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CricViz Analysis: Chasing in the PSL

As the Pakistan Super League continues to be dominated by sides batting second, Ben Jones considers some reasons for this ever-increasing trend.

In a climate where for numerous reasons cricket has not been top of the agenda, this Pakistan Super League season has been quietly intriguing. On the surface, this may not appear to be the case. The quality of the action itself has been solid, if not spectacular; the matches entertaining, if not thrilling; the race for qualification competitive but softened a little by the under-performance of the Multan Sultans. But beyond this, there has been a developing trend that, in the truest sense of the word, has been historic.

As it stands, 81% of matches in this PSL season have been won by the side batting second. Among the six major T20 leagues (Bangladesh Premier League, Big Bash League, Caribbean Premier League, Indian Premier League, Pakistan Super League, Blast), that’s the highest figure for any individual season – ever.

Of course, this does reflect a wider trend in T20 cricket. Chasing sides have found increased success in recent years, as many have noted and many more have lamented. However, that improvement has been gentle and gradual, subtle improvement in the chances of chasing sides over time. Yet whilst the past seven years have seen an evolution in the balance between chasing and defending, this season’s PSL has been a revolution.

Captains aren’t missing this trick. There have been 26 tosses so far this season, and only once has the captain who called correctly opted to bat first. 25 out of 26 times, the toss-winning captain has looked up, looked down, looked at the opposition, and decided to chase.

It has created a slightly concerning bias in favour of the toss-winning side. If the tournament had dispensed with cricket altogether, and simply allocated two points for a won toss, the table would look awfully similar to the actual tournament ladder. The order is slightly altered, but the same teams would be heading through the knockout rounds. Of course, that isn’t ideal.

Yet as with everything in cricket, this has caused a fair degree of angst. People have offered solutions ranging from the removal of the toss to penalty runs for the chasing side, the difference in chance of victory too focused on the toss of a coin – or the flip of a bat. It’s only natural that fans push back against a trend which threatens to make the most unpredictable form of the game more monotonous – but rather than worrying about the effect, it’s more interesting to ask why this trend is occurring.

What outside influences have been acting on the game to force this change, and where has it been felt most keenly?

Well, the difference doesn’t seem to be coming in the Powerplay. Chasing sides are actually performing significantly worse in the first six overs, scoring more slowly and losing wickets more regularly compared to sides batting first. It isn’t fair to attribute their slower scoring rates to a consciously more cautious approach; chasers have attacked slightly more than sides batting first, and with slightly more risk. Given the impact we all know that the start of the innings has on the rest of proceedings (heaven forbid you lose three wickets in those first six overs), it feels intuitive to suggest this is where chasers are establishing their massive advantage. But that isn’t the case.

No, the first time in the innings we see a real gulf start to widen between sides batting first or batting second is after the Powerplay has finished, because in the middle overs it’s a different story. Whilst scoring rates for both sides remain relatively close, dismissal rates suddenly diverge. Sides batting first have lost wickets with alarming frequency, whilst the chasing sides have managed to remain stable.

This pattern is particularly clear against spinners. In overs 7-15, sides batting first have lost a wicket every 19 balls against spin; for sides batting second, that’s a wicket every 29 balls. That is a huge gap. Chasing sides play with significantly more control against the slower bowlers, hitting more deliveries to the boundary and accruing fewer dot balls.

It’s affected even the best performers. The four leading spinners (in terms of wickets taken) this season have been Umar Khan, Mohammad Nawaz, Sandeep Lamichanne and Fawad Ahmed, but the bulk of their wickets have come in the first innings. Their combined strike rate in the first innings (15.3) is significantly worse than their strike rate in the second (21.0). The best bowlers in the competition have been unable to exert the same pressure when defending a total as they have when limiting a target.

There are other moments where batting against spin appears to be an area where chasing sides have held an advantage. The attacking strokes that are played against spin are much, much more secure in the second innings. An attacking shot against spin in the first innings is almost twice as likely to lead to a wicket as an attacking shot in the second innings.

However, for all this, the difference in scoring rate in that middle period wasn’t that significant. 0.45rpo is a reasonable difference, but it’s not vast, and certainly not accountable for 81% of chasing sides coming out on top. However, the natural consequence of losing more wickets in the middle overs is that teams batting first can’t accelerate as well at the death, and this has undoubtedly been the case this season. With more wickets in hand going into that climactic period of the innings, chasing sides are able to score significantly more quickly, largely through hitting more boundaries.

So the main factor in the dominance of the chasing sides, from what we can glean from the numbers, is that middle overs wickets have cost sides batting first dearly.

This effect is then amplified by the lower scores that we have seen throughout the tournament. The high-quality of the bowling attacks, and perhaps the relative weakness of the domestic batting options, have contributed to a scoring rate of just 7.68rpo across the tournament – the slowest scoring rate for any Major League season since the 2016 BPL. It’s important to give some credit to the bowlers in this. The Expected Run Rate (Tracking Only) for this season is 7.01rpo, the lowest figure for any PSL season. What this suggests is that regardless of the batting, the defensive quality of the deliveries has been extremely high. This naturally drives scores down, removing the psychological barrier of massive totals, making it easier to chase.

More broadly, T20 leagues developing unique characteristics is a good thing. The reputation of the PSL as a bowlers’ tournament is great, and offers texture and variety to the domestic calendar. Perhaps the effect of this is that chasing will continue to be more prevalent in the PSL compared to other leagues – the natural effect of that will be that teams scramble to reverse that trend. As teams try more specifically to counteract it, the trend will likely disappear. However, for now, the PSL is a chaser’s paradise – so watch that coin closely, chaps.

Ben Jones is an analyst at CricViz.

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2017 Pakistan Super League Review II

This article is contributed by Imran Khan, who you can follow on Twitter @cricketsavant.

 

Daren Sammy led an inspired Peshawar Zalmi side to take the honours at the second edition of the Pakistan Super League. CricViz takes a statistical look at what took place during the tournament.
General Overview
Peshawar Zalmi’s opening batsman Kamran Akmal topped the run scorers list with 353 runs from 11 innings including two fifties and the only century of the tournament. The next Peshawar batman on the list was Shahid Afridi in 11th place with 177 runs and one fifty. The champions largely relied on one-off performances from their batsman, with Dawid Malan, Mohammad Hafeez, Eoin Morgan along with Afridi all registering one fifty each during the tournament. Peshawar’s relatively modest batting numbers
were generally due to chasing down or defending low scores.

Seam bowlers dominated the top wicket-takers list, with only Usama Mir, Sunil Narine and Mohammad Nawaz representing the spinners.  However, spinners did have a lower economy rate and strike rate than seamers over the whole tournament.  Wahab Riaz and Hasan Ali, who picked up 27 wickets between them, spearheaded the bowling attach for the champions Peshawar. We’ll investigate what made them successful later on.

Kamran Akmal

Tournament top run getter Kamran Akmal was most destructive against right-arm spinners and medium pace seam bowlers, against whom he scored 150 runs at a strike rate of 195.

The beehive plot below shows all of Akmal’s boundaries against these types of bowlers.  He rocked onto his back-foot and seized on anything marginally short from the slow bowlers or went down the track to hit over the top.

In fact, Akmal scored 55 runs from the 36 occasions he played a shot off his back foot against right-arm spinners and medium-pace seamers.  He also accrued 31 runs from the 10 balls he went down the track during the tournament.

Against fast seam bowling however, Akmal was restricted to a run a ball and dismissed three times.

The heat map above is generated from his dot balls against fast seam bowlers with his dismissals in red.  He was generally kept quiet by good to back-of-a-length deliveries just outside off stump.  In fact, from these types of deliveries Akmal scored 46 runs at a strike rate of 90 – well below his overall strike rate of 129.

Akmal was also relatively constrained by left-arm orthodox bowling scoring at a little over a run a ball and being dismissed four times.

The pitch map above shows a distinct cluster of dots and singles (red and blue) where the bowlers like Imad Wasim and Hasan Khan pitched it on a very good length. However, on the few occasions where they bowled full or a touch shorter, Akmal would take advantage.

Chris Gayle

The talk before the PSL was of Chris Gayle’s overwhelming superiority in T20 cricket having scored nearly 10,000 runs in the format.  However, he is still 63 runs short after the end of the tournament having scored just 160 runs at an average of less than 18 and a meagre strike rate of 115.

Gayle struggled against fast seam and off spin bowlers striking at less than a run a ball and being dismissed four times each.

The heat map above shows the distribution of dot balls faced by Gayle against fast bowlers with his wickets in red.  Back of a length and outside off stump is where most of the dots are concentrated.  This is a bowling plan that has historically kept him quiet.  In fact, he scored 25 runs from 24 balls including just 4 boundaries when facing deliveries in this region.

Gayle did not fare particularly well against right-arm off spin and left-arm orthodox bowling.  The heat map above shows that his dot balls generally came when they bowled very straight to him on a good length, again something that spinners have exploited previously.  Of the 21 balls he faced from off spin and orthodox bowling and which were on the stumps, he scored only 12 runs and timed exactly one ball (which was hit for six).

The best bowlers

Top wicket-taker, Karachi Kings’ Sohail Khan utilised his slower ball to great effect.  He sent down 44 throughout the tournament earning him six of his 16 wickets whilst only conceding a run a ball (compared to his overall economy rate of 7.61). Second highest wicket-taker Wahab Riaz fared just as well conceding just 28 runs from his 35 slower deliveries and picking up two wickets.

Sohail Khan’s slower ball was very consistent in terms of speed as the histogram shows above.  Wahab’s distribution is less pronounced indicating that his slower balls were a variety of speeds, with a slight bump at 130 kph.

21-year-old leg-spinner Usama Mir who took 12 wickets for Karachi Kings, the highest for any spinner, predominantly stuck to his stock delivery during the tournament.  However, he did send down variation in the form of googlies and quicker balls a total of eight times, from which he picked up three wickets and conceded only eight runs.

Mir bowled his quicker delivery more than the googly as the very slight bump in the positive spin region illustrates.  Compare this to Sunil Narine who more or less bowled his variations as often as his off-break delivery – something no doubt Mir will gain the confidence to do in his career.

Ground analysis

Every match of the tournament was played on two grounds – Dubai and Sharjah, with the exception of the final which was held in Lahore.  This allows us to reliably compare the two grounds to see how different conditions may have affected team strategies.

The table below summaries some statistics for seam bowlers for all matches in both grounds.  Seam bowlers enjoyed a lower economy rate in Dubai, although at the cost of a slightly higher average and strike rate.

Similarly for spinners, Dubai offered a lower economy rate by 0.5 runs an over, while their average and strike rate were higher.

We can ask whether these differences came about due to the different pitch conditions in the two grounds.  The table below summarises the average off the pitch and in the air movement for seamers and spinners in degrees.

Although Sharjah offered a little more swing for the seamers, they extracted a lot more seam movement in Dubai. Dubai also saw more drift and a lot more spin.

The histogram above shows the distribution of spin at both the grounds.  Both grounds are slightly skewed towards negative values of spin (indicating spin away from the right-hander and in to the left-hander).  Sharjah has a much higher and narrower peak demonstrating the relative lack of assistance from the pitch for spinners.

Importance of the toss

In every game bar one the winner of the toss chose to bowl first.  The table below shows the same attributes from before but separated by first and second innings.

It’s evident that the second innings offered a bit more for every factor but not significantly more – certainly not enough to convince captains to bat first.

As has become a wider trend in T20 cricket, knowing your target is advantageous enough to always bat second regardless of conditions.

The graph above shows the average worm for matches where the team batting second won the game in this year’s PSL.  The green line shows that teams generally start off quicker in the Powerplay before slowing down somewhat to keep wickets in hand until the tenth over.  After this they overtake the first innings worm to chase down their target in the latter overs.

Imran Khan, @cricketsavant

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