Regular By the Numbers reader, spy, had an interesting question for me several weeks ago: “What effect have steroids had on offensive statistics in baseball?“. Its a great question and a really hard one to answer. Noted economist and co-author of Freakonomics, Steven Levitt, has said, “Twice in the past decade, I have really tried to find evidence that say steroids matter in baseball. And both times, I invested a lot of effort, and ended up finding no evidence that steroids mattered.” Instead of attempting to find answers where more accomplished researchers have already looked I thought we might take spy’s excellent question and turn it into an easier and more Orioles-centric one: What happened to the offense in 2010?

It has been widely reported that offense in MLB, in terms of home runs, runs scored, OPS and various other statistics drastically decreased in 2010. In the American League runs per game went down by 0.33 from 2009 to 2010. Furthermore, there has been a gradual offensive decline in baseball beginning in 2007. The graph below shows the Orioles offensive performance in the years from 2007 through 2010 in three major offensive categories. 2010 stands out as a particularly poor year in Baltimore.

While its easy to see that Orioles’ offense was been steadily decreasing from 2007 to 2010 it is much more difficult to determine if this is a result of better opponent pitching, better opponent fielding or poor Orioles hitting. All three are bundled together in a manner that makes it difficult to tease a single factor out. Hayes Davenport of Freakonomics Radio attempted to tackle this question and concluded that improved fielding is the most significant contributing factor to the decrease in MLB offense. However, while improved fielding must have some affect on the MLB offensive decline, there appear to be other contributing factors. Bill Petti, from Beyond the Box Score, recently examined another theory: what if we saw an extreme influx of very good, young pitching in 2010 which caused the decrease in offense in 2010? When Petti asked his question he was concerned with all of MLB. Here, in an attempt to hone our analysis to focus on the Orioles putrid offense in 2010 we will replicate some of Petti’s analysis but restrict ourselves to the pitchers the Orioles had the opportunity to face: non-Orioles in the American League who pitched at least 40 innigs.

In the graphs below we will be plotting Fielding Independent Pitching (FIP). A full primer on FIP is available here. The important point is the FIP is an ERA-esque statistic that only accounts for those events that pitchers have control over (strikeouts, walks, hit by pitches, and home runs). It does account for any fielded ball in play. This makes it an ideal statistic to quantify pitching talent independent of fielding.

The graph below shows the cumulative distribution of FIP each year for non-rookie pitchers in the years 2007 to 2010. The area under each curve represents the percentage (y-axis) of non-rookie pitchers who achieved a FIP less than or equal to the FIP specified on the x-axis. Each curve in the graph ends at the top right hand corner because all American League non-rookie pitchers (100%) have posted a FIP less than or equal 6.8 in each year.

The curves in the above graph are very similar throughout the years. In 2010, more American League non-rookie pitchers posted slightly better FIPs than they had previously, but for the most part the shape of the curves resemble each previous year. The next graph shows the cumulative distribution of FIP each year for American League rookie pitchers in the years 2007 to 2010.

Again, most of the curves look similar except for the large hump in the 2010 curve in the lower left hand corner. This “hump” represents a significant increase in the percent of pitchers who posted FIPs below 3.20. In 2010, 18.2% of American League rookie pitchers posted a 3.20 FIP or better compared to only 10.8% in 2009. This is a significant increase that we did not see in the graph of non-rookie pitchers. Since we did not see such an increase in non-rookie pitchers in 2010 we can safely assume that American League hitters did not experience a similar decrease in their hitting abilities in 2010. Also since we are using FIP our data is independent of any fielding improvements in the American League. Thus it appears the answer to Petti’s question is: Yes. There was a drastic increase in the talent level of American League rookie pitchers in 2010.

Certainly this data does not definitively prove that the Orioles and the rest of the American League failed to score runs in 2010 solely because of a drastic increase in young pitching talent. However, it is very suggestive that the continued decrease in runs we are seeing this year in the American League is due in some part to the outstanding 2010 American League rookie pitching class.