By Mark Grote–

(CBS) Cubs starters Jason Hammel, Jon Lester and Kyle Hendricks have all played big roles in the team’s 2015 success, but there’s something nagging at each.

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Let’s explore further.

Jason Hammel

The mild-mannered Hammel has been caught off guard and perturbed by manager Joe Maddon’s timing lately. In Hammel’s last two starts,Maddon has made the bullpen march to the mound when Hammel has had a lead (2-1 in the sixth inning against Milwaukee and 5-2 in the fifth against San Francisco) and in both cases was safely under 100 pitches (65 and 76).

“I want them to want to fight the manager to stay in there,” Cubs pitching coach Chris Bosio said. “I don’t expect our starters to be happy about coming out early.”

I asked Bosio if he agreed with Maddon’s decisions to take Hammel out when he did.

“There’s a lot of things that are going on during the course of a game that get on our table, but are on Joe’s table,” Bosio said. “We are all supportive of one another, and the bottom line here is that we’re winning games, and Joe is pushing all the right buttons.”

Including Hammel’s.

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Jon Lester

Lester still as that trick-arm problem that triggers adventure when he throws to bases. Lester made a wild fling to first on a pick-off attempt during his start against Milwaukee last Thursday, and the Brewers had five stolen bases on his watch.

“We want our pitchers focusing on the hitters,” Bosio said. “That’s why our pitching staff has had the season that we’ve had. Milwaukee did everything they could possibly do in a game, and they only manufactured two runs. You still want to pay attention to the running game, but the bottom line is executing pitches and getting hitters out.”

That’s what Lester has been particularly adept at recently, with the best proof being his 14-strikeout performance against the Rockies on July 29.

Kyle Hendricks

The brainy right-handed Hendricks thinks he has figured it out. Hendricks was uncharacteristically wild during his start against the White Sox last Friday, when he allowed three walks, five runs and lasted only into the fourth inning.

Hendricks admitted that he hasn’t had the same feel that he had during his 2014 rookie season, when he was 7-2 with a 2.46 ERA, but he’s been investigating.

“I watched some Double-A video, and we (he and Bosio) saw three drastic differences between my mechanics from what I was doing against the Sox, and what I was doing in these Double-A games,” Hendricks said. “Basically, I need to stay taller. Once I get to my balance point and my arm path is getting cut off, it’s too far behind me, to put it in simplest terms.”

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Mark Grote is the Cubs pregame and postgame host on WBBM. Follow him on Twitter @markgrotesports.