I am not smart enough to answer that question, but I tried to figure out how much an effect elite defense has on overall run prevention. I could be way off here, but it seems like at most it can effect it by around 14%.
Here's how I figured it.
If you had a team of gold glovers, they would probably each have a UZR/150 of +10, that adds up to a team UZR of around 100 including all the bench players and pitchers. That's for the best possible fielding team.
The league average in 2009 for runs scored was 727 for the season. So assuming that that league average team had league average defense, if you gave them elite defense, they would save 100 runs, and 100 is 14% of 727.
I could be way off, but that seems like the effect of elite defense on a team's overall run production.
Just for the record, the Reds defense in 2009, according to Fangraphs, was 51 runs better than average, which is damn good. That's half of the very best it could be.
"Imagination is more important than knowledge." -- Albert Einstein