Ferrari has struggled from the start of 2023 with excessive tyre wear paired and 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 in 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.
Source: Autosport