Rookie Shelby Miller’s reassignment to a bullpen role has presented the righthander with a postseason paradox — how to stay game-ready without appearing in actual games.

“It’s different. I’m adjusting to it,” Miller said Tuesday after the Cardinals held a brief and optional workout at Busch Stadium. “I don’t know exactly what my role is. I know that when they call me in there I have to be ready to go.”

Miller pitched an inning in Game 2 of the National League division series against the Pirates and allowed a home run, on his second pitch. Despite winning 15 games this season and the Cardinals going 21-10 in his starts, manager Mike Matheny and his staff opted to use Michael Wacha in the rotation ahead of Miller partly because of the matchup with the Pirates. Wacha took a no-hitter through the seventh inning Monday at PNC Park to stave off elimination and win in his playoff debut.

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For tonight’s decisive Game 5 at Busch, Miller and Game 2 starter Lance Lynn will be available out of the bullpen.

Miller would have been used in Game 3, manager explained, if the team had kept the game tied and needed multiple innings.

“I have no idea when I’m pitching,” Miller said. “Pretty much taking it day by day, keeping it simple. You never know what days you’re going to pitch.”

If the Cardinals are able to advance, Miller could return to the rotation. The Cardinals left that possibility open when announcing the four-man rotation for this NLDS. In two starts against the Los Angeles Dodgers, who await the winner of tonight’s game, Miller had a 5.06 ERA in 5 1/3 total innings.

The righty said he’s modified his routine to be available every day, likening the shift to what he did last year when added to the postseason roster as an injury substitute.

Miller pitched 3 1/3 innings of relief last postseason against San Francisco in the National League championship series. He struck out four and allowed two earned runs. He hasn’t been throwing much before games so that he keeps his arm ready for the game.

The move to the bullpen does put a limit on the young arm’s innings — a priority for the Cardinals all season. He said one bullpen session would get him ready to make a start, if needed.

“I just feel like I haven’t thrown in forever,” he said. “We’ll see what happens.”

AVOIDING BELTRAN

Hours before a walk to Carlos Beltran allowed Matt Holliday to change Game 4 with the game’s deciding swing, Pirates manager Clint Hurdle warned that could happen if the Bucs got too cute handling Beltran.

One of the top postseason performers of all time, Beltran hit his 16th postseason home run in Game 3 and surpassed Babe Ruth for the eighth-most in baseball history. Beltran’s 1.247 OPS in the postseason is the highest in any player’s career, and Hurdle acknowledged that the switch-hitting veteran is close to free-pass status.

“That’s always a tough call for a manager,” Hurdle said. “You believe you can get balls to spots that you can get some outs. Then when you don’t, you’re kind of like, ‘Duh.’ Would’ve. Could’ve. Should’ve. Beltran has been this for years as we’re all aware. … But I do think the problem for me right now is that guy hitting behind Beltran is a good hitter as well. You have to pick which guy you want to go after and which guy you don’t want to deal with. I think it’s a gut feeling.”

The gut went with Holliday in Game 4.

Twice, Pirates starter Charlie Morton walked Beltran to lead off an inning. The second time he did it, Holliday scalded a two-run homer that provided the Cardinals’ only runs. Hurdle insisted after the loss that the Pirates weren’t trying to pitch around Beltran.

“There’s plenty to think about beyond Carlos,” Matheny said.

HOW TO BE A PIRATE

Hurdle has described his players at times this season as having “a lot of Pirate” in them. He was asked Saturday what exactly that meant — whether he was referring to the history of the club or the swashbuckling plunderers for which the club is named.

“I haven’t been able to talk to a real pirate lately,” Hurdle said. “But in the movies that I’ve watched and the books that I’ve read, there seems to be a spirit of ‘I really don’t care what anybody thinks anymore. I’m crossing the line. I’m going to become a pirate. … I’m going to be my own man. I’m going to hope to latch on to a bunch of other men who feel the same way, that are like-minded and try to get something special done.’ Many of those men (in the Pirates’ clubhouse) have gotten to that point in their career.”

EXTRA BASES

Wacha said he didn’t keep a baseball or any other souvenir from his first postseason start. “Just the win,” he said.

• Holliday’s two-run homer on Monday meant Game 4 was the third time in Cardinals history that one swing provided all of the runs in a playoff win. The previous two times were Game 1 of the 1996 NLDS when Gary Gaetti homered, and in Game 4 of the 1964 World Series when Ken Boyer had the grand slam that gave the Cardinals their runs.

• Lefty Sam Freeman threw a 20-pitch bullpen Tuesday. Although he’s not on the active roster, Freeman has remained with the team and kept his arm ready in case of injury or need for a third lefty.

• The Pittsburgh Post-Gazette described Thursday how before Game 4 a young fan, wearing a Cardinals cap, was struck in the forehead by a foul ball during batting practice. The Cardinals who rushed to see if the boy was OK grabbed the hat and passed it around the team. They returned it only after collecting 16 autographs for 11-year-old Jacob Malizio.

Derrick Goold covers the Cardinals and Major League Baseball for The Post-Dispatch. Follow him on Twitter at @dgoold or on Facebook at Facebook.com/BirdLandPD

Derrick Goold is the lead Cardinals beat writer for the St. Louis Post-Dispatch and current president of the Baseball Writers' Association of America.