On a weekend where the championship took another major swing of momentum, here is what we learned.
Ferrari reliability will prove costly in championship battle
Oh Ferrari, what happened again?
More heartbreak for Leclerc who was forced into retirement from the lead for the second time in three races after suffering from gremlins at the Spanish Grand Prix two races ago.
In Baku, the victory was not as comfortably secure though, with Red Bull on an aggressive strategy - a nine-lap tyre overlap that promised a potentially thrilling conclusion to the race, but one we were denied.
In the end, there was no thrilling climax as Leclerc pulled across to the left-hand side of the long start-finish straight with plumes of smoke trailing from his F1-75.
Not only were points lost, critical engine components will also have been damaged beyond repair, meaning grid penalties are inevitable.
Add to this Sainz's hydraulic issue on lap nine and all of a sudden, the Scuderia sits 80 points adrift of Red Bull, a chasm even at this stage of the season.
Mercedes porpoising hits critical level
Russell began the weekend by claiming F1 may need a rethink of the current technical regulations given the vigour of the porpoising affecting some of the grid.
By the end of it, team-mate Lewis Hamilton was barely able to climb from the cockpit of his W13, holding his back as he straddled the halo.
The seven-time champion was in clear discomfort when talking to the media post-race, grimacing his way through questioning, still holding his back.
The question is: Was Barcelona a one-off fix for the team, or is the bouncing purely track - and surface - specific?
Red Bulls show glimpse of cards for first time
If you asked Christian Horner after the Monaco Grand Prix if there were to be any imminent team orders between Verstappen and Perez, he would have said no.
But Red Bull instructed the Mexican not to fight against the hard-charging reigning champion, who went on to win the race and extend his championship lead.
The call was not as egregious as previous displays of teamwork, however, with Perez struggling on his rear tyres after a set-up direction geared towards qualifying left him with worse degradation than Verstappen.
In the end, it was a simple case of avoiding a repeat of the Verstappen-Daniel Ricciardo crash at the same venue in 2018 and with the gap opened to Ferrari so commandingly, the team's move was vindicated.
Vettel proves he is still one of the best in F1
Make no bones about it, what Sebastian Vettel is achieving in the Aston Martin at the moment is nothing short of incredible.
The AMR22 is by no means the most competitive of F1's midfield and the newer specification brought in Barcelona is still in its infancy compared to rival set-ups, with Monaco and Baku not providing the Silverstone-based team optimum opportunity to fine-tune the package.
Yet Vettel scored in Monaco and continued that form with a stunning drive in Azerbaijan.
The German was as aggressive as the driver that clinched four world championships at the beginning of the last decade and was not deterred by a lap-13 excursion at turn three.
Credit must also be given to the Aston Martin strategy team, which navigated virtual safety cars perfectly on the way to sixth.
The beginning of the season was full of retirement speculation for Vettel. If he continues performing as he is now - coupled with his off-track activism - then we can only hope he is around for years to come.
F1's latest political battle takes centre stage
Russell's complaints about porpoising led to a debate in the drivers' briefing in Baku over whether tweaks could be made to the technical regulations going forward.
It is not just Mercedes struggling with the issue, as Haas and AlphaTauri, in particular, are unable to get on top of the bouncing, leaving their drivers in pain.
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