  We propose a method to quantify the Standard Model uncertainty in B to K pi
decays using the experimental data, assuming that power counting provides a
reasonable estimate of the subleading terms in the 1/mb expansion. Using this
method, we show that present B to K pi data are compatible with the Standard
Model. We analyze the pattern of subleading terms required to reproduce the B
to K pi data and argue that anomalously large subleading terms are not needed.
Finally, we find that S(KS pi0) is fairly insensitive to hadronic uncertainties
and obtain the Standard Model estimate S(KS pi0)=0.74 +- 0.04.
