ODT is often proposed for transit deserts, but agencies face a harder “Fix or Flex” decision where FRT exists but performs poorly. Should service be redesigned, or should selected segments be replaced with flexible ODT? This study develops a framework that evaluates FRT performance relatively, rather than through isolated KPI scores. The framework combines efficiency analysis, productivity tracking, and demographic interpretation. Convexity is tested using the FEAR package to determine whether DEA or FDH better represents the transit production technology. A SBM model identifies inefficiency sources such as excess capacity, frequency, kilometers, stops, and service duration. SBM is integrated with the Malmquist Productivity Index to separate persistent inefficiency from temporary changes. Demographic and coverage variables help assess whether weak segments are better suited for FRT redesign or ODT conversion. The framework is applied to MiWay in Mississauga, Canada, using January 2023–September 2024 data across 21 periods. Inputs represent service supply, capacity, stop patterns, duration, and reliability, while outputs capture productivity, cost recovery, reliability, and satisfaction. Convexity tests support DEA for this dataset. Route-level results show stronger performance in central areas and persistent inefficiencies in peripheral zones. Segment-level analysis of 159 segments provides sharper insight. While 87% of routes have average efficiency above 0.6, only 50% of segments do, showing how route averages hide localized problems.