Sometimes teams take a while to understand a new car. See Williams in
'91 - it took them a while to get the best out of that car, but when
they did it lived up to Senna's pre-season judgement that it was
fundamentally a very fast car.
The trouble for Williams was that whilst they were getting the bugs
out of that car Senna won four races on the trot. Williams ended up
with the best car, but McLaren had a big head start.
It maybe that the speed is in the car, but McLaren have to figure out
how to unlock it. Which may vindicate certain decisions but seems
unlikely to gain them a championship.
It's not unprecedented. Newey famously built the car that never raced
at McLaren. At least they figured out pre-season that they couldn't
work with the car and thus updated the previous year's car and raced
that.
In '91 (again) Ferrari realised early on that they had a lemon and set
about designing a new car which they deployed mid-season.
In '94 Williams struggled early on and did major work on that year's
car to make it competitive. Which worked, but without Schumacher being
suspended for two races and being DQed from another they probably
would have not have made up the gap.
IMO McLaren need to make an early call on this. If they dither too
long then the gap between them and the front-runners gets too big.
With the current points system I think the gaps do not grow as big
early on as the other seasons that I've offered as precedents, so it
may be a little easier to recover. I doubt there's much they can do
for the next race.