They do always race against each other until one of the suffers a failure and thus far, Verstappen has always been ahead of Ricciardo. His results could definitely be better than currently is the case.
If, if, if, why this hypothetical reasoning?
It is the same with Ricciardo and doesn't just apply to Verstappen.
What was so special about his race in Silverstone, people were hailing him as if he'd won the race, but he only raced cars that were 1- 2 secs slower than the Red Bull. Formula 1 has a two class hierarchy, class 1 - Mercedes, Ferrari, Red Bull - and then with an exceptional gap there's the rest, as we saw with Verstappen in that race, the Red Bull was capable of fighting the Ferraris.
Raikkonen was 4 secs behind Ricciardo, he didn't have to fend him off. Raikkonen fell asleep at the wheel just like Bottas did look at where their teammates finished the race. That's the reason why there is no need for Hamilton or Vettel to have a clause in their contract stating that they're the number one drivers, because their teammates can't keep up anyway.