Including today's game, they have a .24762 AVG and a .45150 SLG. That gives them an ISO of .20388. That is just actually a little less than the record set by the Mariners in 1997, who had .20413. Their AVG was .28037 and their SLG was .48450. That puts them just 0.00025 ahead of the Blue Jays.
My first post on this was Blue Jays On Record Power Pace.