Ishii's walk rate and WHIP is so high that he is bound to continue to have ugly performances in the second half. The same thing happened last year, he was excellent first half before his luck ran out second half and hitters figured out how to get to him.
I strongly suggest trading him ASAP before his numbers get any worse on the year. A guy with a 9-4 record and 3.34 ERA looks pretty attractive at first sight, especially for guys that don't look at or understand WHIP. If you can't trade him, he's another guy that I'd just dump, because he's sure to do more harm than good to your team in the second half. If you keep him, expect more performances like tonight.
Pre all star break: 11-3, 3.58 ERA (18 starts)
Post all star break 3-5, 5.57 ERA (11 starts)
He's following the same pattern as last year so jettison him ASAP.