Consistency is judged by the coefficient of variation; the smaller C.V. is the more consistent.

Consistency is compared using the coefficient of variation $\text{C.V.} = \dfrac{\sigma}{\bar{x}}\times 100$, not the standard deviation alone (the two batsmen have different average scores, so their standard deviations are not directly comparable).

Batsman A:

Batsman B:

$\text{C.V.}_B = \frac{\sigma_B}{\bar{x}_B}\times 100 = \frac{6}{40}\times 100 = 15\%.$ …

Judging consistency by the standard deviation alone and concluding A is more consistent "because $5 < 6$" — that reasoning is only valid when the means are equal. With different means the coefficient of variatio …