Maddon’s faith in Heyward, and other Cubs notes

Cubs manager Joe Maddon is a long way from having a firm idea of what he wants the last few spots on his playoff roster to look like.

He calls that “an ongoing conversation” as “performance shifts, needs shifts and guys get hurt.”

But know this: Jason Heyward, barring injury, will be in the starting nine for the playoff opener, whether that season-long, power-barren slump continues through September or not.

“Listen, he’ll be the first to tell you he’s not happy with his offensive output,” Maddon said. “But if you’re sitting in the dugout and if you don’t know anything else about him, or his batting average, and you look at our record and you look at him in right field, I can’t be more comfortable with this guy on the field while we’re playing baseball.

“He’s such a good baseball player. He’s such a great teammate — all the things that he does that I believe are really important to victory, to a winning attitude, a winning team.

“I really like his compass.”

The tangible value of Heyward’s game, of course, is the play in the field that continues to put him among the elite defensive players in the game, an historically rare commodity in a Cubs outfield.

It’s disproportionally valuable this year to this team, which figures to rely heavily on the top-performing pitching staff in baseball to win what often are low-scoring games in the playoffs.

“It’s difficult, I know, outside looking in,” Maddon said. “But our record’s pretty good, and he’s been on the field for most of those games. And he’s a winner. He’s an absolute winner, this fellow.”

La Stella day to day at AA

Infielder Tommy La Stella, who on Wednesday ended his 18-day holdout and reported to the minors for his first game since being optioned last month, suffered a bruised foot when hit by a pitch in his second plate appearance.

He was not in Thursday’s lineup for Class AA Tennessee, and Maddon said his status is considered day-to-day.

Big test for Lackey

Before John Lackey’s sore shoulder will be deemed fit to make his pushed-back start Tuesday in San Diego, he’ll have to get through a successful side session either Friday or Saturday, Maddon said.

Lackey (9-7), left Sunday’s start in the seventh inning after the shoulder tightened.

Annual pajama party

Maddon has resurrected the onesies travel-garb theme day for the upcoming trip west.

Almost a year to the day after Jake Arrieta threw a no-hitter at Dodger Stadium, before meeting with the media wearing a mustache-print onesie, the Cubs will wear their 2016 versions on their Aug. 28 flight home from Los Angeles, Maddon said.

Arrieta, by the way, is not scheduled to pitch in that series.

Notes: Despite five runs allowed and a career-high seven walks for Jake Arrieta Thursday, he earned the win – running the Cub rotation’s record in August to 12-0 (16 games). The rotation has a 1.93 ERA this month. … Kirk Nieuwenhuis’ three-run homer off Arrieta in the fourth Thursday was his fifth homer against the Cubs this year. He has six against everyone else. … Madison Bumgarner (2.11 ERA, second in NL) was scheduled to pitch for the Giants Thursday night. The Cubs’ Kyle Hendricks (2.19, third) pitches Friday. And Saturday injured Dodgers ace Clayton Kershaw (NL-leading 1.79) no longer will have enough innings to qualify among the leaders.