Being on the receiving end of a blowout loss was not what she expected.
"We needed to be perfect to beat them and they needed to be under their (usual level)," Begin said. "Too bad but some of my players didn't show up today and they lacked concentration. So that made the difference in goals."
The U.S. led 6-3 at the half and turned it on in the third period with four straight goals en route to a 13-4 rout. Courtney Mathewson and Margaret Steffens led the way with four goals apiece.
Monika Eggens scored twice for Canada. Krystina Alogbo and Joelle Bekhazi added singles in the losing effort.
Asked to expand on her thoughts, Begin said inexperience may have been a factor for some of her players. Playing in front of a raucous near-capacity crowd at the Atos Markham Pan Am/Parapan Am Centre may have taken some adjustment for a team not used to that at home.
"For me it's control of emotion," she said. "Going into the game and controlling your stress, being calm, and applying the gameplan."
The top-ranked Americans outmuscled their opponents in front of the net and were winning the battles for the ball. They also took advantage of some sloppy play and poor passing.
"It's more in executing little simple things," Begin said. "Basic things that you know how to do that we were missing."
The ejection of Canadian centre back Christine Robinson in the second period was also costly. She provides veteran leadership for an eighth-ranked team that has several younger players on the roster.
"I honestly think we just weren't aggressive enough," she said. "As the game started slipping away, I think we kept fighting until the end but it just kind of slipped away slowly, inch by inch."
She was called twice for positional play violations early in the game but the third infraction — for splashing — forced her exit.
"Technically you're not allowed to splash anyone in the face," she said. "I don't think I really did that but I guess that's just me being a little bit biased."
The ejection forced a substitution and a change in defensive alignment. The Canadians couldn't seem to find their rhythm after the move.
The offence was shut out in the third period and the Americans were soon on their way to a successful Pan Am title defence.
"They scored a couple (early) power-play goals that left us reeling," said U.S. coach Adam Krikorian. "But once we got on a roll, we felt really comfortable. I can't say enough about my team."
Earlier, Brazil defeated Cuba 9-6 for the bronze medal.
Begin said there were still some positives to take from the second-place result as her squad shifts its focus to the upcoming world championship in Russia.
"The desire to fight," she said. "Yes, we lacked in concentration and precision but these girls tonight showed up at the game with the right spirit to go and fight for each ball right until the last second even if the score was pretty (lopsided)."
The Americans beat Canada for gold in an epic 20-round shootout at the 2011 Pan Am Games in Guadalajara, Mexico.
The medal games in the men's competition will be played Wednesday. Canada takes on Argentina for the bronze while the U.S. meets Brazil for the gold.
The Americans locked up an Olympic berth after semifinal play Monday night. Brazil already has a berth as the host team.
The women's Pan Am tournament is not an Olympic qualifier. Both Canadian teams will have future opportunities to qualify for next summer's Rio Games.
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