I think you are grossly underselling Russell's value as a passer and defender. He played defacto pg for the Celtics for a few years in the latter part of his career.
Beyond that he is almost definitely the best defensive center ever. Every star center he played against was well below their normal efficiency and scoring volume while being played by Russell.
You can't compare stats across eras without accounting for the incredible evolution in rules and strategy that has happened since the mid 60s. No three point line, more restrictive dribbling, extremely basic play design. I mean Russell coached himself to two championships!!
He was an above average playmaker for sure amongst big men -- I hadn't heard of the defacto PG thing before since they had Jones, Sigfried, and Hondo doing a lot of ball handling in his later years, so I'll have to take your word for it on that one.
He was a great defender for his era but like I said, the only true superstar terror that he had to line up against in terms of big men was Wilt Chamberlain, who averaged 30 PPG and 28 RPG on only slightly lower than career average shooting when he matched up against Russell.
Chamberlain played in the same exact era and was dropping 50 PPG seasons. Chamberlain had a 24/23/8 season on 59.5% shooting in 1967 and he was just as good of a post defender as Russell. There were 115 games where there was shot-blocking tracking for Wilt, and he averaged 8.8 BPG. Russell had something like 77? tracked games and he averaged 8.6.
Bob Petitt played against Russell 68 times in his career and Russell was a primary defender on him most of the time based on the little bit of info I could scour about it. Pettit averaged 28.7 PPG against Russell in his career (FG% numbers are unavailable unfortunately, so I have no clue about the efficiency), but that was two points higher than his career average. Walt Bellamy (24.4 PPG) also averaged above his career high when matched up against Bill Russell (again, I don't have the efficiency). The only "star" big man that I can find from the era that had a significant drop in stats when playing against Russell was Nate Thurmond (16.3 PPG on some paltry shooting numbers).
Russell was 6'10, 215 pounds. Some of that has to do with the era where weightlifting and nutrition didn't sniff what we have today, but like I said, if I'm given the all-time pool of players and all of them are at their absolute peak, I'm going to take prime 6'10 and 265 pounds of muscle Dwight Howard over Russell.
Russell coaching himself to two championships is something I'd file under my original point in terms of overall career accomplishments - something where I'd probably have him in the top-10 for everything that he accomplished and did for the game.
If I'm drafting a team to go out and play tomorrow, Russell isn't even the first center from the 1960s I'm taking.