It's not a "mindset".....
The notion of playing your best available XI from the kick off is going nowhere... It's not old fashioned. It's not like injuries are a modern phenomena either and we've had 25man squads for donkey's years now.
Regardless of the new 5-sub rule; having 2 x world class players in every position is still exclusively the domain of petro-clubs, so the bench is always gonna reflect a drop-off in some areas.
.....Even then Pep has bought players like Ake, Delph, Zinchenko, Torres etc.
....Peak United still had Brown, Fletcher, Park, Raphael etc.
Yes and no.
We are not going to end this transfer window with a 23 man squad with little drop off between players but we are going to end it with more than 11 players with limited drop off - to illustrate the point, assuming a 343 system :
Forwards - Its 3 from 4 players now (Kane, Son, Kulusevski, Richarlison )
CM's - Possibly 2 from 4 players (Bissouma, Bentancur, Skipp, Hojbjerg)
And if we sign a 'creative CM' that some predict we may end by playing a different formation in some games with 3 midfield players and either reverting to a back 4 or the Kulusevski position is replaced by this creative CM
And with the above, Spurs are likely to have a first team where its really 11 players from maybe 17 realistic 'top choices', some of whom will rotate as its not sensible to ply every weekday and weekend (ie 3 days rest between matches, and maybe less due to overseas travel) or rotate if Conte wants to operate with 2 or 3 different formations.
And on top of the 'maybe 17 realistic top choices' there are probably another 6 players who are not quite top players (eg Moura as a forward/wing back).
Of course the 'maybe 17' can only be firmed up at the end of the window.
And that's why Spurs are bringing in the likes of Richarlison to provide real competition and alternatives to Conte so he's not dependent upon picking a first X1 but can pick from maybe 17 players without a huge drop off in quality.
And Richarlison has not come here just to sit on the bench all the time as would be implied by picking the same starting X1, .
Keeps the opposition guessing too.