Kerrigan and first base coach Perry Hill were the only two members of the Pirates' field staff not yet confirmed to return next year. Pittsburgh has not yet made an announcement as it pertains to Hill's status, though the organization has made it no secret that it wants the infield instructor to return for a second season.
As for Kerrigan, he signed a contract -- the length of which is unknown -- after meeting with Huntington in Pittsburgh last week.
"It's been a great experience because of all the young pitchers and their personalities here," Kerrigan said. "These guys have been great. I've really enjoyed it as much as any year I've enjoyed as a pitching coach. I really have, as far as the teaching aspect of it."
The pitching staff has made noticeable strides under the veteran coach, with Ross Ohlendorf and Zach Duke standing out among those who have improved this year.
One year after the Pirates' starters finished last in the Majors with 33 wins and a 5.36 ERA under then pitching coach Jeff Andrews, the team entered this final stretch of seven games with 41 wins and a 4.61 ERA from its starters this season. The team's cumulative ERA of 4.63 is nearly a half-run lower than it was a year ago, and the club is on pace to walk 100 fewer hitters than it did in '08.
That said, a pitching staff that endured its fair share of midseason turnover hasn't been as strong in the second half (5.01 ERA) as it was in the first (4.33 ERA).
"We'll be better," said Kerrigan, who is finishing his 13th season as a Major League pitching coach. "We'll improve. Guys understand the program now. They've been in it for a year. They understand how valuable each pitch is. They know how to track the hitter and what the hitter reacts to. I think they're starting to understand it."
The news of Kerrigan's return goes hand-in-hand with Donnelly's departure. In a decision that was made not by Donnelly, but by the Pirates, the 63-year-old coach was not asked back for next season. Huntington described the decision as a "tough call," but the Pirates had determined to go in a different direction with the focus of that seventh coaching position.
The search will soon begin to fill that vacancy with another pitching coach, one that will be put in position to eventually be a successor to Kerrigan, who is not expected to remain in Pittsburgh long-term.
"We'll probably look to add a pitching guy to the club that can help Joe, but also be mentored by Joe," Huntington said. "Ideally that person can lead into being our next pitching coach if everything goes well. The timing of it is obviously awkward. We thought about waiting until the end of the season, but it is something that we're going to move forward with regardless of Joe coming back or not. So we decided it was best to give Rich the most opportunity to land another job somewhere else."
Donnelly served as the Pirates' bullpen coach from 1986-91 and as the third base coach from 1992-96. After stops in Florida, Colorado, Milwaukee and Los Angeles, he had returned to Pittsburgh in January 2008.
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.