The idea behind this that I recall reading online some place (where, I don't know), is that if a batter has alot of RBIs, it's partly because he has lots of opportunities. Of course, he then has more chances to ground into double plays (the GIPDs). So if he has a high RBI-to-GIDP ratio, it means he is able to drive in alot of runs while not hurting his teams with double plays. It is kind of like a cost-benefit ratio. If you drive in runs you are providing your team with benefits. But if you hit into double plays, your team incurs a cost. By bringing both stats together, I partly offset the opportunity issue in judging the meaning of these two stats. It certainly is not a complete picture of hitting, since getting on base is not well incorporated (and you can drive in runs in non-GIDP situations). But the rankings turned up some interesting surprises, so it was fun to work on.

I did a cursory Google search and I couldn't find where I saw this idea. So I dove in and called up all the hitters with 5,000 or more plate appearances (PAs) since 1946. They had to be divided into three groups: lefties, righties and switch hitters. I used the Lee Sinins Complete Baseball Encyclopedia.  The table below shows the best and worst 25 RBI/GDP ratios for righties (I will just use GDP from now on).

The leaders may not be too big of a surprise. They are power hitters, who get some RBIs with no one base since they hit alot of HRs (but that is still a benefit to the team, regardless of when the runs come). I did try the RBI minus HRs-to-GDP ratio, but the correlation between that and the first measure was about .95. The rankings changed a little, but not a huge amount. There were some good hitters in the bottom 25 and they were not all slow. But those guys tended to not have much power. One player of note, probably the one that was being discussed where I saw this idea, is Jim Rice. He ranked 203rd out of 274 righties. His RBI/GDP was 4.6 and the average was about 5.6.

The correlation between strikeouts per PA and RBI/GDP was about .57. That is not a big surprise since if a hitter strikes out, he can't ground into a DP. But those hitters are often power hitters. The correlation between HR/PA and RBI/GDP was about .69. Again, no surprise (those correlations were similar for lefties and switch hitters).

I also wondered if players who got intentionally walked often could be hurt here since the IBBs might tend to happen when runners are in scoring position. Then they would lose some opportunities to drive in runs. But the correlation between IBBs/PA and RBI/GDP was about .2 for righties and close to that for the other groups. That implies that guys with more IBBs do better in the RBI/GDP. But again, there is a problem. The big HR hitters get the most IBBs and the HR hitters already have a good RBI/GDP. To try to get around this I ran a regression with RBI/GDP as the dependent variable and HRs/PA and IBBs/PA as the independent variables (for righties). That analysis showed a negative relationship between IBBs/PA and the RBI/GDP. It was also statistically significant. I don't want to make too much of this since HRs/PA and IBBs/PA have a correlation of .49, so there could be collinearity.

Now the best and worst 25 lefties.

Things are similar in the case for the righties, except the lefties do much better. The big lead that Strawberry has over Bonds is interesting. He is more than one standard deviation ahead of him. Strawberry must have been tough to double up. The average GDP/PA ratio for lefties was .017. For Strawberry, it was just about .01. His SO/PA was .214 while the average was .119. His IBB/PA rate (.021) was higher than average (.012). But his high HR/PA (.053 vs. the average of .028) combined with his low GDP rate (partly as a result of his SO/PA) are probably what helped him do so well( in the (RBI - HR)/GDP his lead over 2nd place is just about .6).

Some of the top 25 lefties were not big power hitters but they tended to be fast. The bottom 25 again had some good hitters, including three Hall-of-Famers, Gwynn, Boggs and Carew. They are all similar types of hitters-high average and just some power (although Boggs walked more). The worst 25 lefties generally lacked power and tended to be slow.

Now the switch hitters.

The leader, Mantle, is not a big surprise. But I was surprised that the average for the switch hitters, 5.74, was not much above the average for the righties (5.6). The average for lefties was 7.05. Someone considered a great clutch hitter, Eddie Murray, was 26th among switch hitters.