While the use of numbers is a reliable way to determine greatness because of its objectivity, this cannot disguise the subjectivity involved. Reliable methids are not always valid.
Deciding what greatest means is subjective; selecting which numbers to use is subjective; weighting those numbers in relation to each other is subjective; qualifying those numbers in relation to their context in different years is subjective.
My subjective definition of greatest would be having the most positive impact on the most successful teams. My subjective selection of numbers would be +/-, compiled for a season, normalized to the +/- of all team members from that same season, adjusted by a subjective multiplier for the success of the team (championship be ing the highest), adjusted by another subjective multiplier for the competition faced during a season (probably something related to SOS), and added together from all four seasons for a total.
Stewart would have an edge with the successful team multiplier because of four championships. Outside of that I would leave it up to JRRRJ or the reincarnation of Phil to figure it out.