Although there have been several attempts to develop systematic evaluation of control schemes, the choosing and pairing of control variables in chemical reactors is not an easy task. Intrinsic nonlinearities of this kind of systems provoke dynamic responses that are difficult to predict. In this paper, a simple proposition for the evaluation of pairs of control and manipulated variables is developed for nonlinear control affine systems. It compliments the RGA analysis for nonlinear systems because is based on the relationship between zero dynamics and control stability. The resulting strategy is simple, easy to understand and easy to apply for the analysis of control schemes. Also, it is independent of the type of controller used. As an example, it is probed in the evaluation of four control options for industrial FCC regenerators; two of them applied in industry. The results obtained when evaluating the control strategies proposed in four different situations are coherent with industrial practice and operating experience.