Perhaps the best example is Northwestern. Northwestern's law program has made major strides under the leadership of David Van Zandt. It went from being a school of decent reputation with a mainly Midwestern student body to a national university. Median student LSAT went from 165 in 97 to 169 as of this year, and from 14th in US News in 97 to 10th. The jump doesn't seem like much until you realized it leapfrogged real-deal programs like Berkeley, Cornell, Duke and Georgetown. As much as I hate US News, that is a pretty major achievement.
The focus has changed too; it mainly now aims at students with work experience, which, at least in their eyes, leads to a more seasoned, refined graduate.
That said, I don't plan to base my decision to attend on the senior leadership. In the majority of cases, there isn't much relevance. Northwestern is more of an exception than the rule.