The second hitter in the batting order goes to the plate more times than any other hitter on the team except for the leadoff hitter. On average the #2 hitter will have 60 more plate appearances than the #6 hitter, and 90 more than the #8 hitter.
It appears that Dusty Baker intends on having newly-acquired SS, Orlando Cabrera, bat second and 3B Scott Rolen bat 6th. Leaving aside the question of whether the Cabrera signing was wise and whether he should be starting ahead of defensive whiz Paul Janish, should Cabrera be batting second for the Reds?
Let's compare the merits of batting Cabrera second vs. batting Rolen second. Both of these players have long career histories - the "back of their baseball card" as Baker is fond of saying. Cabrera has had over 7200 plate appearances heading into 2010 and Rolen over 7400. Both players are roughly the same age, with Rolen being 6 months younger than Cabrera.
While the two hitters are relatively close in career batting average, with Cabrera at .275 and Rolen at .284, for on-base-percentage Cabrera has a very low .322 while Rolen is well above league average at .370.
One way to put that into perspective is to point out that Willy Taveras has a career OBP of .321. So, over more than 7000 plate appearances, Orlando Cabrera gets on base at the same rate as Willy Taveras.
Another way to view it is to compare Cabrera and Rolen's rates to the rest of MLB. In 2009, 154 hitters had enough AB to qualify for the batting title. Scott Rolen's OBP of .370 ranked him 64 out of 154. Orlando Cabrera's OBP of .316 ranked him 140 out of 154.
Finally, if you're inclined to look at 2010 Spring Training statistics, Cabrera has an OBP of .303 (with three BB) and Scott Rolen an OBP of .375 (with 6 BB, not counting the two he had today).
O-Swing is a statistic that measures the percentage of pitches outside the strike zone at which the player swings. It's a measure of the plate discipline of the batter. Over his career, Cabrera has an O-Swing of 24.3% and Rolen's O-Swing is 19.0%. A clear edge for Rolen.
Since the #2 hitter has more AB than hitters lower in the order, power numbers such as slugging percentage, are an important factor to consider. Over his career, Cabrera has accomplished a .398 SLG, while Rolen has a .498 SLG.
Again, in comparison to the rest of MLB, in 2009, looking at the statistic wOBA which weights OBP for power, Rolen was ranked 49 out of 154 while Cabrera was 140 out of 154.
It's important to note that Scott Rolen has not been the same power hitter since his shoulder surgery in 2005, so his career SLG is misleadingly high. From 2000 to 2004, his slugging percentage was .535, from 2006 to 2010 it was .450. Scott Rolen is clearly not the same power hitter that he was earlier in career, yet Dusty Baker, by batting Rolen in the 5th spot in the lineup apparently continues to treat him as though he is. But even with his reduced post-surgery SLG, he is still more of a power hitter than Cabrera, and by a considerable margin.
These are the reasons that Scott Rolen should bat second for the Reds, not Orlando Cabrera.
(1) Rolen is a better hitter, period. Batting second, instead of sixth, will give him roughly 50-60 more AB.
(2) Rolen will get on base ahead of Joey Votto, Brandon Phillips and Jay Bruce at a much higher rate than Cabrera.
(3) Batting Rolen second will move Jay Bruce up to the fifth spot in the order where his power is more likely to drive in runs.