One of the most interesting recent developments in cricket is the shift towards almost trying to build bowlers out of raw athletic attributes (rather like you see with NFL recruits) rather than trying to pick them out based on their on-field performances at lower levels. Australia and recently England are at the forefront of this: Australia are the best in the world at workload management (most of the time) and have done more than most to nail down what exactly makes a fast bowler successful at Test level, but it means that some of Australia's best bowlers have barely ever played domestic cricket: Starc has played 35 Shield matches, Hazlewood 34 and Pat Cummins only nine in his entire career - less than one full season.
England have recently started to put their money where their mouths are too by picking bowlers like Josh Tongue and Matty Potts based almost entirely on their physical attributes
Currently they are looking for bowlers who can bowl 140 kph from a certain delivery point (I can't remember the height - I want to say 2.1m but idk), and who can maintain a top run-up speed of 23 km/h into their third or fourth spell of the day. The idea of the run-up speed thing is that it distributes the workload more evenly across the bowler's body. They figure they can then refine the actual cricketing skills later, which has been made more straightforward by the advent of the wobble seam delivery. It's not dissimilar to how Duncan Fletcher used to look at the game 20 years ago, but at that point the data science didn't really exist for him to quantify what he wanted.
They're now applying the same logic to the selection of spin bowlers: they are looking for spinners who have high release points (c. 2.1 m); in fact Bashir and Hartley have the two highest in the country. They want spinners who bowl a stock delivery at up to 100 kph, which means that on responsive surfaces the natural variation ranging between 0⁰ of turn and 2⁰ of turn should be enough to make batting exceptionally difficult. Tom Hartley and Shoaib Bashir have been selected based almost entirely on their physical attributes and if one of those spinners actually delivers in India - especially Bashir - it could quite literally change the sport overnight. I expect England to pick Tom Hartley ahead of Rehan Ahmed for the first Test, and if Rehan plays it's as the third spinner.
Regardless of how it goes, this upcoming Test series will have big implications for England and others' future selection policies.