It's statistically illiterate. The difference in sample sizes between the with and without Kane conditions is too large and any properly matched sub-samples are too small. There just isn't the power available to make any good significant inferences from the data we have.I still have nightmares hearing people insisting we are a better team without Harry Kane.
Kane is a proven goal scorer and we just have to find him more. Hopefully we'll see that more at Tottenham with the introduction of Lo Celso Sessengon and improved fitness of Dele Alli
I used to defend stats as a way of analysing football because they seemed to be the best way to reach some kind of objective truth. But I've been on a long many-year journey to changing my mind. The reality is that the vast majority of people don't understand p-values or confidence intervals and, through no fault of their own, simply don't have a sufficient understanding of the maths of probability and statistics to use stats appropriately.
More than that, however, reducing a complex and beautiful sport to a collection of numbers that represent an infinitesimal amount of what's actually going on in a match is crude, not externally valid, and not at all conducive to enjoying the game for everything it is.
Footie stats have spawned an insufferable generation of YouTube kids - well, I hope they're kids - who quite happily argue their respective opinions for hours using almost nothing but numbers. Unlike the older generation, who watched football, these particular kids seem to prefer arguing about it.
Stats (and highlight videos) just enable them to argue for the superiority of their preferred player over another without ever having seen the other player in a real match. As you quantify something, you usually take away from its qualitative spiritual essence and the function of debate. All of this and plenty more "modern" "developments" are contributing to a horrible social culture around football.
Anyway, going back to one of many dumb modern football memes, which is that Spurs are better without Kane: I had hoped the meme would die at the end of last season. Unfortunately, a tragic CL final result from a Spurs team that was hot, nervy garbage from top to bottom fed the exceptionally fanciful idea that things could've been different if Lucas had started -- an idea so stupid that you really had to want to believe it, frankly.
The red pill on last season is that, as far as I can remember, the worst period for Spurs came after Kane got injured the second time. Spurs played six games, winning just one and scoring a grand total of three(!) goals. Kane wasn't there for that nonsense, but it's easy and important to forget that period if you want to construct a narrative (or, indeed, be a sucker for peer pressure and absorb the dominant narrative from the rest of the football fandom).
(It's probably worth noting that these results aren't significant in the grand scheme either but in a world where people's opinion of a player changes after every game, average suckers should be factoring this period into their invalid deductive chains quite heavily)
The claim that Spurs are better without Harry doesn't pass the basic eye test. And that, for me, is almost all that matters nowadays. If you believe otherwise, I've got a question for you: are England better without Sterling because we haven't won any of our other qualifiers - all of which Sterling started - by 7 goals? That's essentially an analogue of the argument you're making in "better without Kane", especially accompanied by "and the numbers prove it".
Sorry for the long response but the Kane memes are particularly triggering to me as a True Kane Believer and scientist.