Before Alexander Steen scored for the Blues at 12:59 of the second period to cut the Predators lead to 2-1, Nashville had 21 of 23 shots on goal following the Reaves penalty.
After coincidental minors against Subban for holding Steen and against Steen for slashing Subban with 31 seconds left in the first period, Patrik Berglund's high-sticking penalty at the end of the period gave Nashville a 4-on-3 power play to begin the second. That man-advantage didn't result in a goal, but it really created more momentum for the home side.
"It got kind of carried over there at the start of the second and we took some more penalties," St. Louis captain Alex Pietrangelo said. "I think again it's the consecutive penalties that we're getting ourselves into trouble. We've got to make sure we keep it 5-on-5 and take away those opportunities."
Blues defenseman Joel Edmundson had a shot on goal with 33 seconds remaining in the first period, but St. Louis never even attempted a shot against goalie Pekka Rinne for the next 9:32, a stretch when the Predators out-attempted the Blues 22-0. St. Louis went 13:32 without a shot on goal before Steen scored.
"That second period really got us there," Edmundson said. "They just kept firing it on net and just kept hemming us in our zone. I think that was their game plan, and we've just got to find a way to get around that.
"We've got to dictate the game. They were more physical than us tonight, and I think that's what kind of backed us off. Next game, we've just got to learn from that."
If not for Allen, who made 31 saves, giving the Blues a chance, it would have been a steeper hole for them. But at 2-1, St. Louis felt good and had plenty of opportunities to score the tying goal before Nashville defenseman Roman Josi scored to make it 3-1 at 14:11 of the third period.
Afterward, the Blues could point the finger directly at not reacting in the proper way, the way they did in Game 2, when they showed discipline, didn't give the Predators a single power play, and rallied in the third period for a 3-2 win.