Yet again read my post, I never said I don't rate Ricciardo but he'd have to have a VERY special season to beat what Sainz managed last year. He drove to absolute perfection in some races, (Austria,Brazil) to be precise.
Sainz didn't really do anything special last year, he was just consistently finishing in 7th and 8th and two good drives where the latter was in the most bizarre of circumstances - he still finished behind a Torro Ross remember. Ricciardo has moved to get out of the Renault seat as i think he can see them exiting the series in the next year. McLaren with a Mercedes engine in 2021 will certainly push them further up the grid. McLaren have improved their driver line up no doubt.
My main point was winning a race isn't the tell tale of a good driver, consistency and good race craft is more important, which Sainz showed in abundance.
I got your point, Maldonado's race win was littered with luck and some strong team calls over that weekend which put the Williams on rails. Winning multiple races is a sign of a good driver, Ricciardo has won multiple races in the same season, some even back to back races. Which makes him a significant step up from Sainz who is still a midfield driver.
What i'm saying is Sainz is going to be very, very good at Ferrari where as Ricciardo will probably only reach a par level, you reach a stage where you're car limited specially in the modern setting.
Make no mistake, Ferrari have a number one driver. Sainz is going to be a clear number two, but a number two that has a better chance of winning races. For Ferrari signing Sainz over Ricciardo means it'll be a less stressful environment as Ricciardo would have put Le Clerc under pressure. However they've gone for stability rather than a race winning pairing, and certainly the cheaper option.