Last season, Sainz appeared pretty much a match for his peer and prodigious team mate Max Verstappen when the outright speed of the two junior bulls was compared.
The Dutch teenager was swapped with Dany Kvyat by Red Bull Racing earlier this year, but the change was by no means a judgment call on the Spaniard's talent or value. As his recent contract extension with Toro Rosso demonstrates, his career as a Grand Prix driver remains firmly on track.
Speaking to SkySports F1 earlier this week, Sainz was asked how he had changed as a driver over the last twelve months.
"From a rookie to the second year you improve in every area, if you say that you haven't, you're lying," Sainz said.
"From qualifying to race, to technical understanding, starts, first laps…you just know how to be in Formula 1.
"Also you learn out of the car a bit more how to behave, how to talk with people, and also the political side of the sport, which is maybe what people don't notice but is also quite important
"All that makes you a more complete driver, a more comfortable driver and also more mature - which is what I think I've become."
The Spaniard believes his development and progress have transpired in his races and performance this year.
"In Barcelona, Monaco and Canada I did three very complete races. No mistakes, good pace, good overtaking, and that in the end is what I think has given me this good run to be in this position now. I also think I have maximised the first laps to gain a lot of places."
While Sainz emphasises his advancement as a driver, he believes however that Toro Rosso has missed a few opportunities.
"We left many points on the table, honestly, in these races - particularly the first four. We were very fast and we just didn't score the points because many small issues were happening.
"Also in Monaco we lost a podium chance which would have given us a lot of points to fight for P5 in the championship. That P5 now looks very solid for Force India, so it's a bit complicated.
"July will be a very important month for us in terms of development of the car. We still have some things to put on and hopefully it will give us a good enough base to keep up this qualy and race performance until the end of the year, knowing that P5 in the championship is now very tricky."