PITTSBURGH -- The Pittsburgh Penguins on Saturday fired coach Mike Johnston and replaced him with Mike Sullivan.

Pittsburgh general manager Jim Rutherford said the primary motivation behind the change stemmed from his feeling the Penguins were not playing up their ability under Johnston, who was 28 games into his second season. Johnston was 58-37-15 record after replacing Dan Bylsma before last season.

The Penguins also fired assistant coach Gary Agnew.

Last season in the Stanley Cup Playoffs, Johnston and the Penguins lost to the New York Rangers in five games in the Eastern Conference First Round and failed to score more than one goal in each of their four losses.

"I want to thank Mike Johnston for his contributions to this team," Rutherford said. "He is a very smart and good hockey guy. I would also like to thank Gary Agnew. I felt with where we are right now, and how we've played over the first part of this season, that this team has more to give. We have some areas where we need to be a lot better. We have to have more will to win. Our power play has to be better.

"Really, over the last couple of games, I saw a team that did have more fight in their game and did have more will to win, but I look at this snapshot over the first 27 games and felt that we've underachieved."

Sullivan, 47, will be introduced as Penguins coach Sunday. In his first season as coach of the Wilkes-Barre/Scranton Penguins, Sullivan led Pittsburgh's American Hockey League affiliate to first place in the Atlantic Division with an 18-5-0-0 record.

Sullivan coached two seasons with the Boston Bruins, winning a division title in 2003-04 and going 70-56-31. He has been an assistant coach for the Bruins, Tampa Bay Lightning, New York Rangers and Vancouver Canucks. He was a player development coach for the Chicago Blackhawks last season when they won the Stanley Cup.

"I believe he's the guy who can come in and really take control and really make some guys more accountable when we're not performing," Rutherford said. "He really is a demanding and take-control guy. And in some ways … he reminds me of a coach that I had a lot of success with, Peter Laviolette."

Rick Tocchet will remain an assistant coach, and Jacques Martin, who served as a special assistant, will be on the bench as an assistant coach.

"I wanted to keep those guys because they know what's gone on here," Rutherford said. "In Mike Sullivan's case, I wanted somebody new that the players won't totally know. That he can come in and mold what we're doing going forward and really take control of the situation of what needs to be dealt with."

The process of considering a coaching change began after the Penguins lost to the Columbus Blue Jackets at home on Nov. 13 and to the New Jersey Devils on the road the following night, Rutherford said. After the 4-0 loss to New Jersey, Pittsburgh held a closed-door meeting which led to forward Evgeni Malkin criticizing its performance and motivation, saying "We're mad at each other."

"I think, for the most part, a lot of our players respected Mike," Rutherford said. "For the most part, the majority of players have done pretty good. … I certainly don't think we've got a huge issue to fix here."

Rutherford said he didn't sense Johnston's altered his coaching style.

"I don't think he changed," he said. "I think if anything, maybe the players changed and maybe understood how to deal with him, or if they did things a certain way or did things their way, that was going to be OK."

Rutherford was critical of Pittsburgh's power play, which ranks 26th with a 15.6 percent success rate. The power play was dormant throughout Johnston's tenure, with the exception of the first two months of the 2014-15 season when it converted at almost 40 percent.

The Penguins have failed to capitalize with the talent on their top power-play unit, which includes forwards Sidney Crosby, Phil Kessel and Malkin, and defenseman Kris Letang, when healthy, Rutherford said. He expressed concern over Pittsburgh's tendency to cycle the puck without getting many shots on net with the man-advantage.

"It actually worked better than anybody would've expected [at the start of last season], not at a pace you could keep up with. It was all new and everybody bought in and everything went to the net, and a lot of times it went in the net," Rutherford said. "As time went on, we got away from that. We have a lot of highly skilled players on the power play who can move the puck around.

"It looks nice, but moving the puck around doesn't help us score goals. … I can't remember the last time I saw a goal scored without a shot on net."

Johnston's system depends on dynamic defensemen who could join the rush, which led to Rutherford taking some responsibility for Pittsburgh's shortcomings. He said he could have done a better job of getting Johnston the defensemen necessary to fully take advantage of his coaching philosophy.

"In fairness to [Johnston], some of this falls on me," Rutherford said. "I didn't get the defensemen that were necessary to have more movement from the back end. I think more puck movement from the back end generates more scoring opportunities. … But at the same time, we have enough offensive players that we should be producing more."

Rutherford said he is unsure what effect the coaching change will have, but hopes to see some players, including Crosby, improve. He has six goals and 19 points in 28 games.

"We never know what a coaching change is going to do," Rutherford said. "I felt that we needed to make a change. I do think we need to get more production out of some guys. But I also recognize that the game of hockey isn't what it was 10-20 years ago, where you have teams dominating games and winning games on a regular basis by three, four or five goals.

"The game has changed. There's more parity. It's a lot tighter. But with that being said, I do expect more production out of some guys."