Bell, there are a few different baserunning stats at Fangraphs. The one you quoted, BsR, is the number of runs a player is worth on the bases, and includes things like taking an extra base, avoiding a double play, not running into an out, and scoring on sac flies, in addition to stolen bases and caught stealing.
There is another stat for the number of runs a player is worth for only stolen bases and caught stealing. It is called wSB. In 2013, Ellsbury was worth +8.3 in stolen base runs and Ortiz was worth +.3 runs. So, for all of his 52 stolen bases, he was worth 8 runs more than Papi. It's not nothing, but it's not as much as most people think it is.