Well here is an interesting question: when was the last time a #2 driver won a title? To my memory, it has never happened.
We came close when Eddie Irvine nearly won in 1999 after Schuey spent the last half of the season recovering with broken legs from that big crach at Silverstone. When Hakkinen eventually won the title, it was alleged that at the time Schumacher asked Ferrari to ensure that Irvine's challenge to Hakkinen was hamstrung just so that he could be the guy who took the honour of scoring Ferrari's first WDC in ages.
Well maybe it was Ayrton Senna. Or Alain Prost. Who knows? Which driver was #2 of that pairing in 1989?