That's kinda why I see McLaren as a good candidate to be the disappointment of the season.
Not that I wouldn't like Norris and Piastri to be given a shot at fighting for race wins on merit next year but I don't quite see many reasons to expect that McLaren will be better than 4th best team. They may be but it's not something that I see as inevitable, Maybe a 30% chance if you ask me.
I think the positivity is due to several reasons, outside the norm of any team over a season/winter break:
They knew and said at the very beginning of last season they had their concept wrong - thats probably not a unique situation internally for a team to know their car sucks before the season starts but certainly unique to pretty much say so at launch
They were confident they would turn it around
Their change in concept didn't bring the usual 0.1 sec with 'we need time to learn the changes in concept' - they worked immediately, and hugely - unlike Mercedes and Aston in particular
They did all this wth the old resources, eg not the new wind tunnel
Subsequent updates continued to work the moment they went on the car, so it's not as if they did one big jump and then immediately hit a wall (like Aston)
They have stated there's more potential there, no reason not to believe them as they have proven themselves so far
They have the technical investment and personnel investment to now tap into
The only question mark for me is the aforementioned investment in both facilities and personnel not muddying their development path... that to me is the only risk against progression