Don't think he seems baffled. Just think he needs to go back and see where the minor tweak needs to be.
The fact that it's not blatantly obvious is more of a good sign than a bad. Last year Farrell could see Lester opening his front leg, dropping his back leg, and flattening out his pitches. That's much harder of a fix than, say, Lester pulling his throwing arm too far back toward 2nd base before he throws, which is what I've heard Farrell say may be the case.