Bowlers win Test matches, and, by extension, Test Championships. India and New Zealand are brilliant, well-rounded teams in all regards, but the biggest reason why they are contesting the inaugural World Test Championship final has to be the potency of their respective bowling attacks. Which one's better? Happily, for anyone looking ahead to the final, there's no easy answer.
The underfoots, the overheads
A bunch of right-arm quicks who generally hit the deck and move the ball off the seam, the world's best offspinner, and the world's best left-arm spinner.
Two right-arm outswing bowlers, a left-arm inswing bowler, a left-arm short-ball merchant, a giant who gets disconcerting bounce and swings the ball, a medium-paced defensive metronome, and a left-arm spinner who's only played nine Test matches.
Given the choice, which group of bowlers would you pick from?
The answer would, of course, depend on conditions. India's fast bowlers are quicker, but New Zealand's are more varied and more adept at swinging the ball. India's spinners are, quite simply, better.
The Ageas Bowl landed the honour of hosting the WTC final chiefly because it has an in-house hotel and is therefore ideally suited to meet the biosecurity requirements of these times. While the ground lacks the history or grandeur of Lord's, the original and natural venue to host such a match, at least one of the two finalists may have been quietly pleased with the switch.
Since it hosted its first Test match in June 2011, the Ageas Bowl has been the second-most spin-friendly English venue in Tests (among grounds that have hosted at least five Tests in this period). It's also been the second-most pace-unfriendly venue in England, with the caveat that all English grounds give fast bowlers something to work with.
Spin has played a major role in India's two Tests at this venue so far, with Moeen Ali picking up eight wickets in a crushing England win in 2014, and bettering that with match figures of 9 for 134 in a tighter contest in 2018, which could have swung in a different direction had R Ashwin been fully fit.
With Ashwin and Ravindra Jadeja in their ranks, India would be thrilled if the Ageas Bowl were to serve up a similar pitch this time around. Simon Lee, the head groundsman, is hoping for pace, bounce and carry, and if that materialises, it could bring both fast bowlers and spinners into play.
The preparation of the pitch, and the extent of wear and tear over the course of the match, will, of course, depend on the weather. Cloud cover on a given day will also have an effect on how influential the swing bowlers will be. New Zealand have the edge in this department, with Tim Southee and Trent Boult in their ranks as well as Kyle Jamieson.
Ishant Sharma and, if he plays, Mohammed Siraj can both swing the ball (into and away from the right-hander respectively) and so can Jasprit Bumrah when he's in peak rhythm (both ways) but that isn't necessarily their primary skill.
Other factors might come into play too - for instance, whether or not New Zealand play both Boult and Neil Wagner. If both left-arm quicks feature (or if there's a lot of right-arm around bowling through the game), Ashwin might have more footmarks outside the right-handers' off stump to aim at as the match wears on.
All-out attack, or the patience game?
Since the start of the WTC, India have been the best fast-bowling team in the world by a distance, when it comes to being a wicket-taking force. Their quicks have taken a wicket every 42.9 balls in this period (all Tests since the start of the WTC cycle).
New Zealand, by comparison, have a collective fast-bowling strike rate of 55.3 across their WTC Tests and their two non-WTC series against England. That's roughly an extra two overs per wicket. Their economy rate of 2.67, however, is the best of all WTC teams, while India have conceded nearly a third of a run more per over, going at a collective 3.00.
Both pace attacks have varied component parts, of course, but each attack could be considered to have an overarching style, born of the conditions and circumstances they're used to bowling in.
India's quicks are happiest when they attack the stumps and bring bowled and lbw into play. ESPNcricinfo's ball-by-ball data bears this out when you group all balls deemed to have pitched on the fuller lengths (full-toss, yorker, full and good length) and arrive at a wicket-to-wicket line as "balls attacking the stumps". Since this relies on subjective logging of line and length, it isn't the most precise measure - unlike, say, ball-tracking data that predicts exactly how many balls will end up hitting the stumps - but it's a useful tool to test broad hypotheses.
By this measure, since the start of the WTC, India's fast bowlers have attacked the stumps with 20.05% of their deliveries, the highest percentage of any Test team. At 17.45%, New Zealand's fast bowlers rank above only those of Bangladesh, Zimbabwe and West Indies. It isn't a surprise, then, that New Zealand's quicks are met quite often by batters offering no stroke - more often than any other pace attack, 26.28% of the time.
There are two reasons, possibly, for this relatively high left-alone percentage. One is the composition of their attack, which usually contains two left-arm seamers, which often means - especially when the ball is older and isn't swinging a lot - a high proportion of balls slanting away from the right-hand batter. Two, New Zealand's home pitches tend to flatten out significantly as Test matches progress, and second-innings bowling can turn attritional. Their bowlers look to play on the batters' patience outside off stump, or - Wagner in particular - pack the leg-side field and pepper batters with short balls. Both these strategies can lead to a high proportion of balls left alone.
India's fast bowlers tend to bowl more attacking lines - which come with a smaller margin for error and a greater likelihood of leaking runs - because their home pitches, which don't usually offer too much bounce, demand it, and because they have the luxury of operating in short, sharp bursts at home, where the spinners take on the bulk of the workload.
But they've found a way to bowl the same way away from home too. Pitches in Australia traditionally reward the relentless pursuit of the outside edge, but India went there at the turn of the year and won a Test series largely by sticking to their strengths, attacking the stumps with the protection of extra leg-side fielders.
There is, clearly, no one "correct" way. As divergent as their methods have been - and consequently their strike rates and economy rates - India's fast bowlers (21.47) and New Zealand's (24.65) both have outstanding collective averages since the start of the WTC.
Allrounders, and bowlers who can bat
India's only series defeat during the WTC cycle came on their 2019-20 tour of New Zealand. There were other factors behind their 2-0 loss - injuries to key fast bowlers at inopportune times, the poor form of most of their top order - but perhaps the most significant one was the relative depth of New Zealand's bowling resources in their own conditions.
Jamieson made his debut in the first Test in Wellington, took four first-innings wickets including those of Cheteshwar Pujara and Virat Kohli, and became undroppable even when Wagner - who missed that game - returned to the side in Christchurch. New Zealand left out their spinner instead and went with four frontline quicks plus the medium-pace of Colin de Grandhomme, and that depth of seam bowling made a key difference on a green, bouncy surface, against an India attack that featured three quicks and a spinner.
India could play four quality fast bowlers if the conditions in Southampton were to demand it, but it would leave them with an inordinately long tail, especially now that they've left Shardul Thakur out of their 15. Through some strange quirk of fate, none of their other fast bowlers is a reliable lower-order contributor even though all their spin options are allrounders to varying degrees. This situation is even starker on this England tour, with neither Hardik Pandya nor Bhuvneshwar Kumar part of their squad.
New Zealand have left Mitchell Santner, their spin-bowling allrounder, out of their 15 for the WTC final, but they have a genuine seam-bowling allrounder in de Grandhomme, and in Jamieson a fast bowler with immense batting ability. Southee, Wagner and Matt Henry, meanwhile, are all better lower-order batters than the bulk of their Indian pace counterparts.
If conditions bring spin into play, India will have little trouble in putting out an attack that ensures they have both bowling and batting depth. New Zealand, however, can be more flexible with their selections. They could pick three seamers plus Ajaz Patel and de Grandhomme, or four seamers and de Grandhomme, or take the adventurous option of batting Jamieson at No. 7 and picking their four best fast bowlers and Patel.
Either way, they'll have tough choices to make. de Grandhomme could be particularly hard to leave out: since his Test debut in November 2016, his economy rate of 2.39 is the joint-best (alongside James Anderson's) among bowlers who have taken at least 30 wickets in that time. He swings the ball, often coming on as first change ahead of the likes of Wagner, and gives nothing away while giving New Zealand's main fast bowlers breathing space.
The capacity to surprise
Since the start of 2018, Wagner has pitched nearly 49% of his deliveries in Test cricket on the two shorter lengths (short/short of good length). No surprise at all. But during New Zealand's just-wrapped-up series victory in England, Wagner's percentage of short and shortish balls came down to just over 21, as he bowled for the most part like a traditional left-arm swing bowler.
This move was dictated by the Dukes ball - which retains the integrity of its seam far longer than the Kookaburra that's used in New Zealand - as well as the pitches at Lord's and Edgbaston, which weren't outright greentops but still offered enough seam movement to discourage any major deviation away from traditional modes of attack.
A lesser bowler may have struggled to make that switch, but Wagner is good enough to operate in an entirely different manner to the one that's defined his Test career.
And that, really, is the crux of it. These are two sets of bowlers with tremendous ability, experience and know-how, and it isn't wise to pigeonhole any of them.
Wagner is more than just an enforcer. Ishant turned himself into an entirely different bowler a decade into his Test career. Southee is the most classical of outswing bowlers, but watch out for that three-quarter-seam ball, and the utter precision of that surprise bouncer. Bumrah showed up on the first morning of his fifth Test and demonstrated the miracle - with that action? - of his inswinger into the left-hander, Keaton Jennings his unsuspecting and utterly befuddled victim. In the lull of the early months of the Covid-19 pandemic, Jamieson taught himself to swing the ball into the right-hander. Ashwin, appearing an unlikely starter at the beginning of the 2020-21 tour of Australia, ended it as one of the key players in India's Test series win.
As the WTC final draws nearer, there is much delight to be had in the anticipation of the familiar: close-ups of Mohammed Shami's seam position, perhaps, or the joyous elongation of Boult's follow-through when he's beaten the bat. But there is the thrill of the unknown too, the possibility that we may be witness to a match-changing, career-defining moment of invention or reinvention.
Karthik Krishnaswamy is a senior sub-editor at ESPNcricinfo