"We do after the five races now have a much, much better understanding of the vehicle, of what we need to do to get the auto to be working - but we still have learning to do, improvements to be made".
Vettel got off to a great start this season, winning the first two races, before his fortunes changed for the worse.
Bottas posted a 1m16.904s to lead the way on the supersoft compound tire, a lap time that would have been good enough for seventh on the grid in Sunday's Spanish Grand Prix on the same tire. In China, he couldn't manage more than eighth place after an ill-timed safety vehicle and a subsequent collision caused by Max Verstappen.
Despite his slow start, people often forget that Hamilton was robbed of a race win in Australia, after dominating the weekend from start to finish.
Bottas secured his 25th podium in Spain and, while he was not completely satisfied with the result, he is determined that his first win is just around the corner.
Vettel gave away his position when Ferrari chose to go for an extra stop and give the German driver fresher tyres. "The Red Bulls are really fast in the final sector and it's going to be really hard to beat them". "We had to stop again and we obviously lost two positions, and also a bit of time during the pit stop itself".
After Mercedes outpaced Ferrari throughout the race weekend in Spain there were suggestions that Pirelli's decision to bring thinner tread tyres gave a benefit to Mercedes.
Renault, meanwhile, will use current F1 star Carlos Sainz on the opening day, and 24 hours later British-Korean Jack Aitken, racing in F2 with ART Grand Prix this year, will get his first taste of contemporary F1 machinery. But, repeating their Spanish performance in Monaco will be easier said than done for Mercedes and it may yet be too early to hail this as a turning point in their campaign. As I said it was good in terms of timing, coming from a poor weekend for us, we were not quick enough and more than not being quick enough we were struggling to make the tyres last - these things have a link - so it was good to have a possibility to revisit it and now it's up to us to take action.
Behind Vettel and Bottas, Ferrari's Kimi Raikkonen was keeping the error-prone Verstappen at bay, with the Dutchman beyond the DRS range of the Finn.
Haas' Kevin Magnussen was over 1.5 seconds down on Hamilton, finishing narrowly ahead of home favourite Fernando Alonso as McLaren enjoyed a more positive outing. "Calmly, we need to analyze the reasons, and they are various, which prevented us from exploiting the potential we demonstrated in the previous races".