The news comes less than a month after the team dismissed five coaches -- Rick Aponte, Pat Corrales, Lenny Harris, Jerry Morales and Tim Tolman -- after it finished with a 59-102 record this past season.
"The [new] coaching staff has a combination of youth and high energy," Acta said. "It was a good process where we came up with a good group of guys that will help us turn it around."
Riggleman, who will be the bench coach, has nearly eight years of managerial experience. His best season came in 1998, when he guided the Cubs to the postseason. He last managed this past season, with the Mariners, and he is still a candidate to return to that position. If that happens, the Nationals could turn to Willie Randolph to serve as their bench coach.
"I agreed to take [the bench coach job], but I'm still holding out some hope that I could go back to Seattle," Riggleman said. "That decision is going to be up to [general manager] Jack Zduriencik and the Mariners front office; that would be to go back and manage. There will be a lot of candidates for that."
Riggleman is considered an "old school" manager who loves to bunt and steal bases. The Nationals are hoping to do more of that next year.
Grissom has accepted his first job coaching at the professional level, and he returns to the organization that drafted him in the third round of the 1988 First-Year Player Draft.
Grissom, who will be the first-base coach, was known as a natural clubhouse leader during his playing days with the Expos, Braves, Indians and Giants. All of those teams were playoff contenders when he was with them.
Grissom was hired to improve the outfield defense and baserunning. Acta often complained about his team running into outs, and members of the media and the front office often questioned why center fielder Lastings Milledge, for example, was often playing close to the warning track.
"All [Grissom] has done is teach his whole life," general manager Jim Bowden said. "He is a leader in the clubhouse. Marquis will be the guy that Milledge, Elijah Dukes, Willie Harris, Emilio Bonifacio and Ryan Zimmerman will really listen to."
Listach -- who comes highly recommended by Cubs manager Lou Piniella, who is one of Bowden's mentors -- will be the third-base coach and infield instructor. He joins the Nationals after spending the last three seasons compiling a 231-189 record managing in the upper levels of the Cubs' farm system.
"Piniella swears that [Listach] will not only be a good big league manager, but a phenomenal big league manager someday," Bowden said.
Eckstein, who will join the staff as a hitting coach, is known for helping Ryan Langerhans and Kory Casto improve at the plate. Zimmerman and outfielder Austin Kearns were also impressed with Eckstein when they had rehab stints with Triple-A Columbus.
The Nationals finished near the bottom in almost every offensive category this past season, and Eckstein wants to see more consistency from the hitters.
"There is a level of consistency that needs to happen, especially on an individual basis, and that comes in many forms -- whether it's a mentality or something physical or a plan," Eckstein said. "One of the things that goes into being a hitting coach is just a matter of me sitting down with the player, the organization and Manny, and coming up with a plan to figure out how to be more consistent and put things together."
Zimmerman has high praise for Eckstein.
"He is very good at what he does," Zimmerman said. "He notices a lot of small things that nobody I've worked with has noticed before. I think that's the biggest thing in hitting. He does a good job of noticing those things. He is very smart and intelligent for what he does."
Knorr, 39, returns to Washington as the bullpen coach, a position he filled on Frank Robinson's coaching staff for the final three-plus months of the 2006 campaign. Knorr is fresh off guiding Class A Potomac to the Carolina League championship in his fourth season managing in Washington's farm system.
The Nationals announced on Sept. 28 that Randy St. Claire would be retained as the pitching coach, citing his tutelage of such young pitchers as John Lannan, Joel Hanrahan and Collin Balester. The longest-tenured pitching coach in the National League East, St. Claire will be spending his seventh season as the franchise's pitching coach in 2009.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.