He drove very well, but keeps getting this season invalidated due Verstappen'd failures. Well, people weren't paying attention when Ricciardo had 5 DNFs, one less than Max, in the time when the car was at it's best. I don't know if he'll (or even Max) will win a title, but for now he seems a better driver than Max.
You need to look where Ricciardo DNF'd from compare to Verstappen
Australia - Was starting in P15 - probably could have got up to around P7
Russia - Was running in P7 behind Massa - with Massa's puncture would have been sixth behind Max
Hungary - Was in P4 when he was taken out by Max - could have finished third
USA - Likely to finish in P3
Mexico - Likely to finish in P3 - Max won the race
Compare that to Max
Bahrain - Was P4, set to undercut the Mercedes, P2 on the cards
Spain - P3 was likely considering his pace advantage over Ricciardo
Canada - Was set for P2
Baku - Would have won the race due to chaos - P1, retired from fourth
Austria - Qualified sixth before clutch failed
Spa - Was fifth ahead of Ricciardo - was on for P3
Singapore - Was second before the Ferrari's turned into him. A win was on the cards.
Looking at this Max had 2 wins robbed from him and 3 other podiums. Ricciardo just lost three third places.
Overall I rate Ricciardo's season an 8, was generally a bit behind Max, but still had some awesome races