Back of Cubs' rotation struggling to keep up with front

PITTSBURGH — If Jon Lester and Jake Arrieta proved in back-to-back games that they’re ready to drive the playoff bus for the Cubs’ starting rotation, the rest of the starters proved only that it might be a pretty small bus.

When Kyle Hendricks got rocked for three innings Thursday in a game the Cubs came back to win 9-6, he became the fourth consecutive starter not named Lester or Arrieta to last fewer than four innings.

To be fair, one of those was reliever Travis Wood, who pitched into the fourth inning on a bullpen day Saturday in Philadelphia. But underscoring the point, Wood was the only one of the four to pitch effectively (three scoreless).

The back three of the rotation — Hendricks, Jason Hammel and Dan Haren — combined for just 9⅔ innings in their three starts, allowing 12 earned runs, 18 hits and six walks (11.17 ERA).

The only reason the Cubs won even one of those games was because the lineup teed off on Pirates starter Charlie Morton and the middle relievers Thursday.

It was an especially discouraging finish to a 7-4 road trip for the threesome, each of whom had turned in an encouraging start in his previous assignment.

Manager Joe Maddon doesn’t seem to be considering any 11th-hour changes to the rotation looking ahead at the playoffs.

But lefty Clayton Richard (2-0, 3.00 ERA in three starts for the Cubs this season) earned the win Thursday after pitching 3⅓ effective innings. He sailed through three scoreless innings before putting two of the first three on in the seventh. And Trevor Cahill (two runs in 8⅓ innings) has shown flashes of his former All-Star life.

The Cubs already are planning a bullpen day Saturday against the Cardinals, providing an opening to try out an alternative.

“I saw him primarily in Oakland when he first started, and he was nasty,” Maddon said when asked about giving Cahill a start in the final two weeks to evaluate options. “I’m seeing really good stuff; it’s not an anomaly. We may give him that opportunity. I don’t know yet. But I think he’s really important to what we’re doing.”

If anything, Maddon said, Cahill might be looked at as a solution for some of the Cubs’ late-inning questions.

Soler activated

Instead of waiting until they got home for the series opener against the Cardinals on Friday, the Cubs found a flight to Pittsburgh early enough Thursday for rehabbing outfielder Jorge Soler to join the team.

Soler (oblique) had been on the disabled list since Aug. 24, his second DL stint of the season. He went 3-for-13 with two doubles and three walks in four playoff games for advanced-Class A Myrtle Beach.

Maddon said he doesn’t know what Soler’s playing status will be because of the addition of outfielder Austin Jackson.

Kang out for season

A Pirates infield that already had endured lengthy injuries to two key players took another hit Thursday when Rookie of the Year candidate Jung Ho Kang reportedly suffered a torn left medial collateral ligament and fractured tibia. His loss will affect the middle of the Pirates’ order and its depth.

The Pirates’ infield was intact and healthy again for less than three weeks when Kang, batting cleanup and playing shortstop, took a double-play feed from second baseman Neil Walker and got hit in the left knee by a hard-sliding Chris Coghlan. He completed the double play but left the game.

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Email: gwittenmyer@suntimes.com