Again, between passing Perez and Gasly's driveshaft failure Verstappen took out almost 10s from Bottas, Hamilton and Vettel:
http://en.mclarenf-1.com/index.php?p...tteri%20Bottas
If that doesn't tell something about the current RB package competitiveness than I don't know what will.
I reckon they will need or are going to improve more than the competition on the following:
1 Tyre understanding/management, closing the gap to Mercedes on difficult tyre tracks.
2 Further improvements in aero effectiveness/consistency.
3 Further engine performance improvements.
Point 2 has already improved a lot from Bahrain testing after the first few races. I expect them to make good gains again in Barcelona. Peak drivetrain output for Q3 and critical race stages will still be a challenge for the time being I reckon. However if they can compensate sufficiently in the above area's I see them regular winning races in the short term.