This is a very interesting stat but as mentioned above, those plays are never going to be ruled as DI so while the % of successful steals seems high, that result is tainted by the number of times there is no throw to 2nd.I have play-by-play data from the WCWS since 1997, and I've found this statistic to be fascinating.
Only one player has been thrown out trying to steal second with a runner at third in the last 25 years at the WCWS. Those attempting to steal 2nd are successful 93 of 94 times with a runner at 3rd. That's compared to about 71% success rate when no runner at 3rd.
Still seems like a really high number though.