Given an instance I of an optimization constraint satisfaction problem (CSP), finding solutions with value at least the expected value of a random solution is easy. We wonder how good such solutions can be. Namely, we initiate the study of ratio ρE(I) = (EX [v(I, X)] − wor(I))/(opt(I) − wor(I)) where opt(I), wor(I) and EX [v(I, X)] refer to respectively the optimal, the worst, and the average solution values on I. We here focus on the case when the variables have a domain of size q ≥ 2 and the constraint arity is at most k ≥ 2, where k, q are two constant integers. Connecting this ratio to the highest frequency in orthogonal arrays with specified parameters, we prove that it is Ω(1/n k/2) if q = 2, Ω(1/n k−1− log p κ (k−1)) where p κ is the smallest prime power such that p κ ≥ q otherwise, and Ω(1/q k) in (max{q, k} + 1})-partite instances.