Squad depth is not two 60m U23 wingers "battling it out" for the same spot. It never works like that. At Chelsea, with the addition of Victor Osimhen, it's not really 10 players for five spots as much as it's eight players for four spots, because Palmer and Osimhen will start every league game they're fit for.
Maresca said Sterling is not the type of winger he likes, as a reason for sidelining him, but there are several wingers in the squad who are clearly worse for any tactical system than Sterling is.
The question then is, if Sterling is not a winger that Maresca likes, is Sancho a winger he likes? Sancho is less effective than Sterling at almost everything. While there are situations the former Borussia Dortmund winger will thrive in, Chelsea is not likely to replicate that environment.
Chelsea is a very competitive environment, and not particularly in a good way. When 10 senior forwards are fighting for the five spots, things become very intricate when some of them start performing well. For example, Palmer has already cemented his place in the squad, so whatever position he plays is out of contention.
Osimhen, by being the striker the entire Chelsea board traveled to Napoli for, will start the majority of games. This means the striker position is no longer in contention. This then leaves Felix, Madueke, Neto, Mudryk, Chukwuemeka, Jackson, and Nkunku, and Guiu to fight for three other spots. If one of them plays well enough to cement his place, it becomes seven attackers for spots.
Sancho offers nothing to Chelsea that should make Todd Boehly and Behdad Eghbali want to add him to the fray.