Some information on Kleyn from two years ago via TGG.
TGG: "Kleyn, who has worked for the club since September 2017, revealed that the club use three ‘waves’ of metrics to measure team performance: traditional event data, XY data and tracking data."
"Each is "useful for different reasons" and has "a varying level of complexity”, meaning that “from a data point of view, what we were able to do very quickly was to apply our first team data model to our B team,” Kleyn explained."
“This was really powerful," he added, "because it provided use with a ready-made tool to check that transition tactically. It allows us to use internal comparisons, so we can compare the first team with key metrics to the B team and interpret the differences.”
"Kleyn, who worked for Norwich for three years before joining the Saints, used pressing metrics in his presentation to illustrate how the B team, who play in Premier League 2, has become more closely aligned tactically to Hasenhuttl's first team than the U23s were previously."
The high press is fundamental to Hasenhuttl’s style of play, as enshrined in the Southampton Playbook.
"The diagram below compares the pressing of the first team and U23s last season, with red indicating a high amount of defensive pressure and blue a low amount of defensive pressure. As you can see, there were major differences in what is a fundamental of Southampton's senior style of play."
"What we’re seeing here is that the U23s became the B team who were immediately able to show that they were capable of more aggressive pressing style of play this season."
https://trainingground.guru/articles/how-southampton-use-data-to-align-their-first-team-and-b-team