His K/9 is definitely going to come back down to earth. His velocity hasn't changed from last year, his SwStr% is around career norms, and he's throwing fewer pitches in the zone.
However, Jack Moore over at FanGraphs writes:
There's certainly reason for optimism. In addition there are 2 big things that I can take away from looking at his stats:
#1. Big leap in first pitch strikes. This started last year and really amplified in June. Getting ahead in the count has made a huge difference for Clay. This looks stable.
#2. Big decline in Swing %. Jack notes Buchholz has done a good job painting corners, but it's also been the movement on his pitches landing anywhere in the strike zone. You know how a batter will admit he was fooled by shaking his head after a swinging strike? I've seen more head shakes, deep breaths, and other assorted dejected body language from hitters on called strikes. Clays pitches are dancing. Pitch looks like it's outside the plate, and breaks into the strike zone at the last possible moment. This is where the doctoring accusations become really interesting IMO. He's already made 2 starts post allegations, going 14 innings with a 3.85 ERA, 1.29 WHIP, and 13 K's. Not terrible, not great either. Of course 2 starts isn't a lot to go on.
I'd like to see 3-4 more starts before making a firm declaration on his outlook for the rest of the season. If I had to make a decision right now, I'd sell high if possible. When in doubt don't trust a 6 week sample size. From here on out I'll project a 3.55 ERA, 1.25 WHIP, and a 7.2 K/9. Still a perfectly solid starter, but not an ace.