Eiland persuaded Hammel to abandon his closed-shoulder stance in his setup and encouraged Hammel to use a more squared-up approach.
The difference in Hammel's pitches was noticeable on Wednesday. He went six-plus innings and gave up six hits and three runs. Hammel didn't strike out a batter in his previous outing over six innings. But this time, Hammel struck out seven.
"Personally, a good step forward," Hammel said. "Good curveball, good slider, good changeup. Fastball had good downward action.
"The extra side sessions I got in really helped. I made the adjustment to get more square with my shoulders. Last year, I made the adjustment to close up my shoulders because normally I fly open so much. So I was basically trying to give myself more time, but it made it too long to catch up with my back side. I started getting too comfortable with it and I was missing too much arm side. So we opened it back up.
"Everything I threw tonight was breaking downward. My fastball ... I didn't miss up much."
The only real mistakes Hammel made were two two-seamers to red-hot Didi Gregorius, who homered in the third, and doubled and scored in the seventh.
"He's so hot right now," Hammel said. "It was basically the only two fastballs that I yanked and they came back out over the outer third."
In the end it didn't matter much in the outcome: The Royals were stymied by Yankees right-hander Luis Severino, who threw eight shutout innings.
"But I've got to keep the ball in the yard no matter what the other guy is doing," Hammel said. "You give up a homer and that's still a point for the bad guys.
"A loss is never good, but it's something I can build on."
Jeffrey Flanagan has covered the Royals since 1991, and for MLB.com since 2015. Follow him on Twitter @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.