Chennai Super Kings rode their luck to the playoffs and Rajasthan Royals were unlucky not to have made it to the playoffs of IPL 2019, according to ESPNcricinfo's Luck Index. Royals only marginally avoided the wooden spoon this season, but were at the wrong end of a few lucky breaks for the opposition that flipped the results against them. Had these events not occurred, Royals could have notched up a net of two additional wins, which would've taken their points tally to 15 - enough to carry them into the playoffs. Super Kings, on the other hand, could have been knocked out of the IPL at the end of the league phase.
One defining moment that epitomised the season for Royals and Super Kings came in the match between the two teams in Chennai. With Super Kings already floored at 27 for 3 in the fifth over, MS Dhoni got an early reprieve on zero: a delivery from Jofra Archer rolled back on to his stumps but the bails didn't fall. Royals had had Chennai Super Kings on the mat by then, and Dhoni's wicket would've reduced Super Kings to 27 for 4. Luck Index estimates that Dhoni's reprieve cost Royals 15 runs. This cost is arrived at by assuming that Dhoni is dismissed and simulating the rest of Super Kings' innings. The remaining balls in the innings are allocated to rest of the batsmen, and an estimate of their scores is calculated. Needing 12 to chase down off the last over, Royals ended up losing by eight runs. The result of the match could well have been different had Royals had to chase 161 instead of 176.
That game was just one of the several fortuitous instances for Super Kings this season. In another example of how the rub of the green went their way, Shane Watson's 96 won them a match, having been reprieved against Sunrisers Hyderabad, in Chennai. The home team were chasing 176 and secured the win with just one ball to spare. Luck Index estimates that Super Kings ended up scoring 31 runs more than they would've had Watson's catch been taken.
Had things panned out differently, Super Kings would have had two fewer wins to show for their efforts this season than they actually managed. Considering that Sunrisers could've ended up with a net of one additional win and already had a much superior NRR, it was quite possible that Super Kings would've been eliminated at the end of the league stage on the basis of NRR. The below graphic shows how the points table would've looked at the end of the league stage after taking out all the luck events for the teams.
This is not to say that Super Kings didn't deserve to be in the finals. Chances are worth as much only when they are made use of. Super Kings' batsmen top the list in terms of extra runs that were added to the team's total thanks to those reprieves. Incidentally, these chances came in matches where the additional runs mattered, often in relatively low-scoring games.
To illustrate this, let's look back on the qualifier against Delhi Capitals. Watson got a reprieve in the first over of the chase, with a run-out chance. He went on to score 50 off 32 balls after that. Twenty-four of those runs came in the last nine balls he faced and sustained the momentum Faf du Plessis' had given to Super Kings' innings in a do-or-die contest. Luck Index estimates that that Watson innings shaved off 18 runs off Super Kings' chase, without which it would have been a far tighter affair.
Contrast this with Ishant Sharma's drop of Ajinkya Rahane in the game in Jaipur. Rahane went on to score a century after benefitting from the chance in the fifth over. Luck Index estimated that the chance added 33 runs to Royals' total. But unlike in Watson's case, those 33 runs came in a match where both teams scored over 190 runs and the home team's total in the end was not enough to win them the match.
The below table shows the top batsmen whose reprieves were impactful for their teams. The Impact Runs column is an aggregate of the additional runs their teams ended up scoring because these batsmen got reprieved. The third column presents the Impact Runs normalised for result margin and the relative size of the target set up in the match. In the match against Sunrisers, the normalized value for Watson's Impact Runs of 31 are normalised to 15. This is calculated by dividing the impact runs by margin of win and then adjusting by a factor for the size of the target. This takes both the importance of the runs, to the win margin, and the size of the target into account. In the words, the same Impact Runs would have higher normalized value should it come in a close match in a low-scoring game than if it were to come in a high-scoring match. Evidently, Watson's reprieves were more useful to Super Kings than those of other batsmen to their respective teams.
Watson is not the batsman to have the highest aggregate Impact Runs this season, though. Andre Russell, in fact, leads the list. Russell's chances benefitted Kolkata Knight Riders by 141 runs. But two of those chances, while adding big runs to Knight Riders' total, were immaterial when seen in context of the match. In the game in Chennai, Russell got a reprieve that added 42 runs to Knight Riders' total - the highest any chance has cost this season - but the team could put up a total of only 108 runs even with that chance. The Super Kings to chase down without breaking a sweat.
The other big chance came against Royal Challengers Bangalore when he was dropped in the 14th over. Russell clobbered 54 from the next 17 deliveries he faced before getting out on the penultimate ball of the match. Knight Riders, however, managed just 13 out of the 24 required off the last over. Russell's chance resulted in additional 30 runs to Knight Riders' total, but those runs were not enough to take them over the line.
Overall, some of the other teams were recipient of at least as many chances as Super Kings had, but the ones the losing finalists converted proved more consequential. Super Kings were fortunate enough that their batsmen made use of their luck in crunch situations, as Watson did, again, in the final. But in that game it wasn't enough to take them over the line.