I think the problem was not strategy, it was the car. It was just slow (and no, Sainz is not that slow. Remember he’s the only non-Red Bull winner this year, and he’s been really close to Charles all year, Charles being one of the fastest drivers on the grid).

They even had to retire the car at the end, so, something was clearly not working. Maybe they expected to go faster, but realized there was something wrong, and eventually gave up with it. It was a sad end of season for Sainz, who, other than the last two races, has had a really consistent season so far.