ut only slightly so than that of MBAs.= but only slightly better than the failure rate of MBAs. that of 的that指代 failure rate so = better 尽管(虽然)这些科学家们的失败率低些(好些),但是也只是比MBA(工商管理硕士)的稍微好一点点罢了.
这个 so 不是跟 than that of 一起断句的,应该是: the failure rate of these scientists, though, was better, but only slightly so / than that of MBAs. 但是,这些科学家的失败率比MBA的要好些,但只好那么一点点。 so 指代 better, slightly ...