The 28-year-old defenseman and captain, who led the Blues in average ice time per game (25:44) for the seventh consecutive season, believed change was imminent after St. Louis (44-32-6, 94 points) missed the Stanley Cup Playoffs last season for the first time since 2010-11, finishing one point behind the Colorado Avalanche for the second wild card from the Western Conference.
O'Reilly was acquired in a trade from the Buffalo Sabres for forwards Patrik Berglund, Vladimir Sobotka and Tage Thompson, a first-round pick in the 2019 NHL Draft, and a second-round pick in the 2021 NHL Draft. The Blues signed unrestricted free agents Bozak (three years, $15 million), Perron (four years, $16 million) and Johnson (one year, $1.75 million).
"On the hockey side, I think you bring in a couple guys that want to be here and add some depth at the center position, which is what we needed," Pietrangelo said. "To see ownership give [general manager] Doug [Armstrong] the OK to do what they have to do to improve this roster is a pretty good feeling knowing that they got the guys that were out there, to have guys that are excited and want to be here and be a part of this team knowing where we are.
"It's pretty good because they want to win, they know we have a chance and we have a good roster. This is kind of the next step that we can take."
O'Reilly led the NHL in face-offs won (1,274) last season,and his 59.98 face-off win percentage was second in the NHL to Anaheim Ducks center Antoine Vermette among those who took at least 200 (60.00).
O'Reilly had 61 points (24 goals, 37 assists) in 81 games. Bozak had 43 points (11 goals, 32 assists) in 81 games for the Toronto Maple Leafs. Perron had an NHL career-high 66 points (16 goals, 50 assists) in 70 games for the Vegas Golden Knights. Johnson was 10-16-3 with a 3.55 goals-against average and .891 save percentage for Buffalo.
"Obviously we know what Perron brings, but O'Reilly and Bozak, we know they're two-way players," Pietrangelo said. "Having played against them, I know how good they are on the defensive side. They're very, very difficult to play against."
The Blues ended last season with Brayden Schenn, Kyle Brodziak, Sobotka and Oskar Sundqvist as their top four centers. Schenn, O'Reilly, Bozak, Robert Thomas (chosen No. 20 in the 2017 NHL Draft) and Ivan Barbashev make up the group for 2018-19.
"I think a big element that we were missing that we've added now is face-offs," Pietrangelo said. "Not only are you just bringing in face-off guys, you've got a right-handed [Bozak] and a left-hand (shot, O'Reilly). That may be another element that goes unnoticed to the normal eye, but that's a big, important thing for us knowing you have a guy that can go win a face-off on both sides of the ice. It's good to see that we've addressed those needs and I'm excited to see these guys up the middle because they want to take care of the defensive end just as much as they want to score goals, which I think is championship hockey."
