so what sample do we use? take last years and this years data and the BB/9 is ~4 and K/9 is > 6.
with dynamic systems, it is appropriate to give a higher weight to the more recent data and if there is a marked change in the data, the data from before that point should be disregarded. applied to pitching, if a guy suddenly develops an effective knuckleball to go with a 93 mph fastball, all data from before the knuckleball was developed should not be considered when predicting the future.
sanchez appears to be improving start by start, looking at his overall results doesn't tell us anything about his future. at this stage of his career, as a rookie starter and making adjustments start by start, his overall stats for the year are essentially meaningless