The 18-year-old trailed Massa over the first six Grands Prix of 2017 - but with the Brazilian eliminated in Canada, Stroll brought home Williams' only points in ninth place. He says that result was a turning point for his self-belief - which has only been boosted by qualifying eighth in Azerbaijan.
"I think it's time, experience... I gain every time I get in the car," Stroll said of his improved performance.
"Canada was great for my confidence, and I've felt more comfortable this weekend - jumping in the car in FP1 I felt really confident immediately with the track, the balance - everything just came together. And today was obviously a great day too.
"I missed out a bit in Q3 compared to my Q2 lap, I didn't feel I was able to get the tyres working perfectly and it was a scruffy lap from my side. But all in all very happy with it."
Stroll says he and the team have also been able to make progress with set-up - which he feels is a natural part of the process of adapting to F1 as a driver.
"This weekend we came back to the set-up from a few weekend's ago," he explained. "When you're young in F1 and new to it, you need to discover what's good for you. Sometimes it takes a couple of weekends off where you should be to figure 'this is better'.
"We're a team, we do it together at Williams. We take the direction we think is right - that's how it goes. We're only eight weekends in, and this is hopefully a long-term project.
"Today I'm just really happy with the result. Obviously the race is tomorrow, that's when we have to score points, but very happy with today."