Rarely do coaches single out the importance of one player, but the Blues' Ken Hitchcock readily admitted before Game 3 Thursday that his team's Western Conference semifinal series turned when defenseman Alex Pietrangelo was hurt. Pietrangelo suffered a knee injury in the second period of Game 1 against Los Angeles when Dwight King pushed him head-first into the boards. Pietrangelo stayed in the game for one more face-off, a play that resulted in a shorthanded goal. Including that goal, the Kings went on to score seven times on their next 27 shots with Pietrangelo out of the lineup. "We were thinking about this yesterday ... (Game 1) is 1-1 and we're probably playing better than they are," Hitchcock said Thursday. "(Pietrangelo) goes out and this whole thing changes. It's hard to believe that one player makes that big a difference. But this series changed dramatically with that one play. For whatever reason, we haven't been able to get back up to speed back there." Pietrangelo returned Thursday, playing nearly 19 minutes, but that wasn't enough for the Blues as they lost 4-2 to fall behind 3-0 in the series. LA took the opener 3-1 and then blasted the Blues 5-2 in the second game. Pietrangelo finished the regular season with 51 points, leading the club in even-strength ice time (24 minutes, 43 seconds).He was second in power-play ice time (2:52) and second in shorthanded ice time (3:12). "When you have a player who touches all three aspects of the game: five-on-five, PK and PP, and then he leaves the game quickly, there's a huge adjustment phase that you have to go through," Hitchcock said. "In the regular season, you can get away with it. But here, you can't. I think we got exposed a little bit. We had players who weren't able to play against some of their top guys and we got scored on because of it."