Ferrari has struggled from the start of 2023 with excessive tyre wear paired with a lack of consistency in its race pace.
That meant the Scuderia has struggled to convert its often-impressive qualifying speed into sustained race pace over a full grand prix distance.
The team has been restricted to just three podiums, all through Charles Leclerc, who took two of his top three berths after falling back from pole.
It kicks off the second half of the season in fourth, five points behind Aston Martin and 56 behind Mercedes.
According to team-mate Sainz, who has yet to replicate his season-best result of fourth from the opening race at Bahrain, Ferrari now has a grasp of its car's core problems.
But understanding its wild inconsistencies is now a top priority, so the issue doesn't carry over to the 2024 project.
He conceded that the SF-23 is still a "very peaky car" which has made it very confusing for the team to predict which circuits it will perform well at.
"The core problem of the car, we do understand what it is," Sainz said, ahead of this weekend's Dutch Grand Prix at Zandvoort.
"Since the first developments of the year, we are trying to get it better. And the whole development programme has been focusing on improving that main weakness that we have.
"I think it's no secret now that this year we've lost like some consistency from the car.
"It's very difficult to predict which circuits we're going to be quick on and which we're not going to be quick.
"There's the wind sensitivity, there's the track temperature sensitivity that we have, which at the moment makes it a very peaky car.
"The best example was the difference between Hungary and Spa. We expected Hungary to be a good weekend, we expected Spa to be a weaker one.
"And it was actually the opposite, which shows that there is maybe something intrinsic that we don't fully understand and we cannot predict very well."
Sainz explained that Ferrari is now using every Friday practice session over the remaining 10 races of this year to experiment with its set-up to find more answers that can help the 2024 car.
"We've done 12 [races], we still have 10 to fully get to understand everything," the Spaniard added.
"This unpredictability, this lack of understanding is exactly what we are focusing on now to try and piece together everything. And this is where our focus is going to be this weekend and obviously, in the second half of the season.
"Every weekend in F1, FP2 we are trying something different to try and understand these regulations and try to see where we may be lacking compared to obviously the reference Red Bull and how we can make the 2024 car quicker.
"I think we're doing a pretty good job of trying completely different things and having different theories that we're putting together for next year's car. Hopefully next year it pays off."
Team-mate Leclerc pointed out that Ferrari is not the only team to go through dramatic form swings this year, meaning that if the Italian squad can get on top of its inconsistencies, its results could improve dramatically amid a tight battle behind the dominant Red Bulls.
"For now, the short-term goal is to improve our consistency because if you look the first part of the season, you look McLaren, Mercedes, Aston Martin and ourselves, then everybody is really inconsistent," he said.
"One race, it's McLaren that is going to be on top by quite a bit and the other race is going to be us or Mercedes that is going to be on top.
"If we manage to find what we have in the car that gives us the consistency to always be on top of our game, this will give us a big upper hand compared to the other teams, so that's where we need to focus on at the moment."
Additional reporting by Matt Kew
