Since Mike Schmidt hit 548 career HRs, and Sinin only returns a total of 515 for him here, it appears that he's accounted somehow for the fact that he also played a little bit of 1b, 2b and ss (also, presumably pinch hitting).  I played with it a little and Sinin shows him with 0 HRs at 2b and ss and 33 at 1b.

> According to Lee Sinins sabermetric encyclopedia,
> 1    Mike Schmidt                515  

Evidently, Sinins identifies players with fielding positions, at least
at the career level.  That can only be controversial.  In real life,
you need to think about what you mean --probably in reference to real
players such as Harmon Killebrew, Dick Allen, Tony Perez, Joe Torre,
and someone who played 40% third 30% left 30% right-- *and then* use
some database management ingenuity.