I know that in the DCU the Time Masters were called the Linear Men, but maybe the requirement for a great Time Master is non-linear thinking. So Rip's fly-by-the-seat-of-his-pants style might have made him a great Time Master because he didn't think ahead in straight lines.

Rip might be a master of noncausality. However, the other Time Masters we've seen resemble the old Guardians of the Universe, in being fuddy-duddies and fuss-budgets.