Coincidence or not, the transformation has happened in his first full season as a relief pitcher.
Miller has pitched in 49 games for the Red Sox, all in relief. He has a 3.29 ERA and a .191 opponents' batting average. The lanky lefty has notched 47 strikeouts in 38 1/3 innings.
"Ultimately, I think some of the adjustments I've made the last couple of years are paying off and I've thrown the ball the way I think I'm capable of doing it," Miller said. "I think my stuff is back to the level I felt like it should have been for a long time."
Manager Bobby Valentine has found Miller to be a mid to late-inning reliever he can count on.
"I think Andrew has developed into a terrific pitcher," Valentine said. "I think he started in a very questionable place and now has a real secure foothold on being able to compete at the Major League level."
Miller, 27, thinks his improved arm slot has had perhaps more to do with his turnaround than the switch in roles.
"I just think I got in some bad habits," Miller said. "I just think I was costing myself a lot of power. It doesn't just take power off your fastball. It makes your breaking pitches worse. I think just getting my arm slot to a lower level, probably where it was five, six years ago, has been the difference-maker. I'm just trying to keep things simple."
The immediacy of life in the bullpen is something Miller has taken to.
"It's kind of been nice coming to the park every day knowing there's a good chance I'm going to pitch or at least have to get up and be ready," Miller said. "I think that helps prevent the mind from wandering a little bit. I think a lot of times it's tough as a starter. If you're not doing well, you have four or five days to think about it. As a reliever, you have a rough one, you'll be back out there pretty soon and you have to get over it."
It remains to be seen how Miller will be used going forward, but he's clearly proven to be a viable reliever.
"I think he could be a dominating force in the bullpen," Valentine said. "I'm not sure how that would translate as a starter."