"I'm just going to let it be a mystery," Miller said at the Cardinals' Winter Warm-Up on Sunday. "A mystery unsolved."
Miller's non-usage became a secondary storyline as the Cardinals played deep into October. Despite winning 15 games, making 31 regular-season starts and posting a 3.06 ERA, Miller was left out of the rotation in the National League Division Series. There was a valid explanation for that, as the Pirates had beaten Miller four times in 2013.
Miller pitched once in relief during that series. He wouldn't take the mound again. Not only did the Cardinals opt to exclude him from the rotation for the two playoff series that followed, but they also chose not to utilize him out of the bullpen. The most vivid memory of Miller's October was watching him warm up in the eighth inning of Game 6 of the World Series. The Cardinals were down five runs at the time.
"The season just kind of ended, and I kind of just put it in the past," Miller said. "I was a little upset I didn't pitch. I put it away. That was however long ago it was. After the season ended, I wanted to be ready for a big offseason and getting ready for the spring. I didn't want to dwell on the past as far as not pitching in October. I'm not going to go up to anybody and ask about it anymore. I'm not worried about it anymore."
Miller reiterated that, physically, he "felt amazing" over those final weeks. He conjectured that his workload may have been a factor in the Cardinals' decision, given that he had already set a career high with 173 1/3 innings during the regular season.
Despite his end-of-the-season perplexity, Miller said he does not believe his October disappearance is reflective of an organizational change of thinking about his long-term value.
"The four guys we had throwing were doing really well," Miller said. "[Adam Wainwright] is always going to throw [well]. [Michael] Wacha was doing great. Joe [Kelly] was having a killer end of the season, and Lance [Lynn] was a guy who's been around that kind of atmosphere and pitched in that. If you're asking if I've lost my role as a starter or anything like that, I don't think so. We're going into camp battling, just like I pretty much did last year, with even more guys."
Miller, whose 2013 season was recognized by a third-place finish in the NL Rookie of the Year voting, will report to Spring Training again in a rotation competition. Last spring, he beat out Kelly in the battle for the fifth starter's spot. The rotation picture is a bit murkier this year, only because there is less definition in the order of the starters behind Wainwright.
Certainly, the resume that Miller produced last season will factor into the Cardinals' decision about where he will fit in April. He's a favorite to retain a rotation spot.
"I'm really looking forward to seeing the adjustments he makes through the season coming up, learning from his last season and all that," Wainwright said of Miller. "The reason I say that about Shelby is I just think sometimes we forget what he was able to do for us last year. Winning 15 games as a rookie is pretty awesome."
Miller is preparing for the season similarly to last year. After seeing the negative effects that slimming down had on his performance in 2012, Miller has spent the past two winters putting on muscle. He has maintained a weight of about 225 pounds but described himself as "stronger than I was last year."
Miller said he hopes that with added strength comes extra endurance. Nearing 200 innings would be a natural next step for Miller in his second full season as a member of the big league rotation.
He's also shooting for October -- this time to spend the month as a participant.
"I had a good season, and I want to be that much better," Miller said. "I want to win 20 games next year somehow. I want to be a part of winning a World Series and all the good things and all the right things you want to say. It's tough to not get to pitch in the postseason, but at the same time, we had a good thing going."