Olson has an OPS of 1.193 with runners in scoring position this season; Kim's is .727. So yeah, Olson's hitting is making up for his "bad" defense. All first basemen get dinged defensively for playing first base; all second basemen get a boost for playing up the middle.
If you'd like to read about it more, here you go:
In essence, the positional adjustment is a correction to account for the fact that different positions are more challenging than others, which is a pretty easy thing to accept.
library.fangraphs.com
The difference between a center fielder and corner outfield is 10 runs even though they are fielding just one extra ball on average every two games. All of the calculations need to be updated, badly.