It's not his stuff, it's that he needs to throw first pitch strikes and work ahead in the count. In the other series, he did and his curveball was very effective. This series but for an inning or so he's worked behind, they've laid off the deuce on the corners and put good swings on it when he throws it over the middle half.
To me it looks like he's trying to be too fine, and falling behind. The first pitch doesn't need to be on the paint, most hitters will take a pitch that's not in their wheelhouse for a called strike one. Then, he's ahead, hitters get more anxious and his stuff looks better to the ump.