ESPNcricinfo’s Smart Stats uses Pressure Index values to decode the two half-centuries in India’s first T20I win
ESPNcricinfo Stats team25-Jan-2020Shreyas Iyer has undoubtedly, and deservedly, sealed his claim as India’s new No. 4 in limited-overs cricket with his composed innings under pressure in the first T20I of the series against New Zealand. He walked out to bat at 115 for 2, with 89 to get from 60 balls but was to lose the senior batsman in Virat Kohli soon after. India had to get 83 off 53 balls when Kohli got out, and those kind of chases have been iffy when one of their top-three batsmen aren’t around. So there was pressure on Iyer alright.Iyer was awarded the Man-of-the-Match prize for his 29-ball 58*. But was Iyer’s the most impactful innings from India’s batsmen in the match? ESPNcricinfo’s Smart Stats reckons otherwise, and puts KL Rahul’s 56 as more valuable than Iyer’s knock, given the context of the chase.ESPNcricinfo Ltd
The Pressure Index and Impact
ESPNcricinfo’s Smart Stats uses an intelligent algorithm that quantifies the pressure a batting team or a batsman faces at every ball in the innings. It takes into consideration the runs to get, overs remaining, the value of batsmen’s wicket, the quality of bowling with overs left taken into account, and the quality of the batsmen yet to come among other things, to arrive at a specific Pressure Index value for each ball. This value is always between 0 and 1. The closer this value is to 1, the more the pressure on the batting team and the batsman. Based on the Pressure Index and the batsman’s performance under those circumstances, Impact % is calculated.
According to ESPNcricinfo’s Pressure Index algorithm, Rahul’s innings came during a passage of the chase when the scoreboard pressure was higher, quantified by the algorithm with the average Pressure Index value of 0.61. The average Pressure Index value when Iyer was at the crease was 0.48. Therefore, Rahul’s innings had a higher Impact value, 22.3%, as compared to Iyer’s (16.4%).Popular opinion might lean towards Iyer’s innings as being the one of more value because it came under greater perceived pressure, but let’s do some digging to see if it’s backed by numbers that aren’t hidden inside the black box of a capable, yet admittedly complex algorithm.
ESPNcricinfo has ball-by-ball data for 512 T20 chases of targets of 200 or more. Only 61 of these chases have been successful — that’s 11.9%. The median runs hit in the first ten overs of these successful 61 chases? 104. Which means in half these successful chases, the team has scored at least 104 runs. In only one-fourth of these chases, teams have hit at least 111 runs in the first ten overs. Rahul led the chase for India in the first-ten overs that saw them score 115 runs — four more than what one-fourth of successful teams manage to achieve.Alternatively, teams that score 115 or more runs in the first ten overs of 200-plus chases have ended up winning 13 out of 25 times. That’s a success rate of 52%. In other words, Rahul’s innings oversaw a phase for India when their chances of winning the match went up from 11.9% to 52%.Compare this with what Iyer had to deal with when he came in to bat. India required 89 from ten overs, and to put that ask in context: teams needing between 75 to 90 runs in 200-plus chases have been successful in five out of eight cases. It’s an equation in favour of the chasing team, especially with seven-eight wickets in hand. Teams chasing 200-plus targets (ending up successful or otherwise) get 85 or more runs in the last ten overs half the time anyway.This juxtaposition of the challenge faced by the two batsmen is what the Pressure Index part of the ESPNcricinfo’s Smart Stats module encapsulates. Rahul’s innings came under greater scoreboard pressure and hence, had more impact than Iyer’s.
