When Ellsbury played for the Red Sox, he was the elite base stealer in the game. After him and one or two others, the dropped off was huge. I' d be willing to bet that the stats for Ellsbury's positive effect on the lineup were very similar to those for Billy Hamilton, which are significant. Expanding the number of base runners in this instance is one of those circumstances where the larger sample size is less reliable, because the expanded group isn't comparable to Ellsbury (2008-2013) or Billy Hamilton.