I was just looking through some data and noticed something cool. In 2009, Reds pitchers faced fewer batters with runners on base than they did in 2008. Why is that a big deal? Well, for one, the 2009 pitchers had more walks and hit by pitches (10.3% walk+HBP rate compared to 9.8% in 2008) and fewer strikeouts (17.1% strikeout rate to 19.3% in 2008), which means not only were they putting more men on base, but they were also allowing more balls to be put into play than in the previous year.
And yet they faced just 2785 batters with men on base, compared to 2989 in 2008.That's 200 plate fewer plate appearances with men on during the season, a number that is due almost entirely to improved defense behind pitchers. While 200 PA over a season might not be a huge amount, it's a big deal when you have pitchers that are prone to giving up the long ball.
The Reds do have a few of those types of pitchers to go along with a park that gives up a few of its own too. However, this table below shows how a having a strong defense can even help on HR:
|Year||Bases Empty||Men On||% with Men On|
Some of the difference is not strictly because of better defense. Reds pitchers had the highest percentage of flyballs turn into HR in 2008, which is generally considered unlucky more than poor pitching. That number was much more normal in 2009, so that is part of the reason for the decline in home runs allowed. However, there is a connection between facing fewer batters with men on and allowing fewer multi-run home runs. Limiting issues early in the inning can help avoid bigger problems later in the inning.
What's the point of all of this? Well, I think some fans are still trying to understand the significance of defense beyond platitudes like "Defense wins championships" and complex ideas like saying the Reds defense saved 95 more runs in 2009 than 2008. Hopefully this can give you a concrete example of how improved team defense can change the success of the pitcher. It's not simply a matter of getting that specific hitter out, but making the situation easier when facing other hitters later in the inning. Call it the butterfly effect of baseball defense.