I did a search and found no discussions of how much difference it makes whether a player's speed rating is, say, 62, or 75.

I did a quick survey with a small sample and found that Chipper Jones 2008 at speed rating 57 batting leadoff scored once every 6.7 PA whereas Jim Edmonds 2004 at 75 speed batting 5th needed only 4.75 PA to score a run. Let's state that as 57-6.7 vs. 75-4.75. That's a big difference.

But at the same time, I found McGraw (1999) 86-5.42, Sosa (2001) 62-5.6; Bonds (2001) 69-6.05; Wheat (1924) 69-6.45. (Sosa's relative success might be due to context, as he's batting 4th on an offensive team with the most wins in its league.)

I'm guessing that the difference between 68 and 74, or 65 and 72, may be meaningful over the length of a season.

Any thoughts or information?

I have to think about it a bit more. I like the idea you brought up and how you came up with a measurement tool of sorts.

It appears that context may override speed alone. I just realized I should compare Wade Boggs with someone fast.

Boggs in 1988 scored 128 in 719 PA, slightly better than Lou Brock's 126 in 720 in 1971. Boggs is rated speed 57, Brock 92.

In WIS performance history, Boggs averages 121/641AB vs. Brock 127/668 AB.

My conclusion, Boggs' extremely high OBP trumps Brock's speed.

But what about John McGraw? Higher OBP and fast? His WIS performance average is 135 RS in only 509 AB.

Given similar OBP, it's clearly better to be fast than slow. How many runs might McGraw have scored leading off for the Bosox in 1988?