The rookie centre-fielder from Mississauga, Ont., figured in four of Atlanta's runs. He misplayed Jonny Gomes' first-inning fly ball with the bases loaded that resulted in a three-run double. Then in the third, Pompey's throwing error brought Freddie Freeman home for the Braves' fourth run.
"We lose that game because I don't make that play and I take full responsibility for that," said Pompey, who began his availability by apologizing to Toronto coaches, players and fans. "I kind of stopped for a second and broke back and the ball started to slice back to my reverse side and I couldn't make the adjustment in time . . . I should've been playing deeper in that situation but I wasn't.
"I made a bad throw also. It's a learning experience for me but unfortunately it was one of those where I feel like I cost the team a chance to stay in the game."
Pompey, 22, admitted he's been playing scared this season, afraid to make mistakes. But he said Sunday's miscues reinforced the importance of playing aggressively and living with the results.
"It shows me I just need to be more aggressive and if I make mistakes being aggressive then it won't be as bad," he said.
Pompey wasn't the only Toronto rookie to struggle. Losing left-hander Daniel Norris (1-1) allowed five runs (four earned) on six hits with two walks and a strikeout over 2 2/3 innings.
"I'm going through a little bit of a dead-arm phase," Norris said. "It's something where you feel 100 per cent fine but it (ball) doesn't come out like it usually does.
"Even if I throw and it says 93 or 94 (miles an hour) it doesn't have the same life on it and I can't really command it like I'm used to. It's mentally exhausting going out there trying to do something to give you a little bit of momentum. You can't do anything to fix it, you just get through it."
Toronto manager John Gibbons said teams must take the bad along with the good when playing rookie players.
"They're here for a reason, we like them," he said. "If you're committed to them you've got to be able to live with it.
"There are going to be days like that."
A bright spot for Toronto was left-hander Jeff Francis of North Delta, B.C., whose contract was added from triple-A Buffalo earlier Sunday. The 10-year veteran become the 22nd Canadian to play for Toronto, allowing two hits while fanning three and walking two over 3 1/3 scoreless innings.
"He kept us in the game," Gibbons said. "He really saved our bullpen, we were pretty short there so that was good."
Francis' appearance gave Toronto three Canadians on the field — along with Pompey and Toronto-born catcher Russell Martin — for just the second time in its history.
Atlanta (8-4) took two-of-three from Toronto (6-7), which dropped to 2-5 on their 10-game homestand. Right-hander Shelby Miller (2-0) got the win, allowing two runs and five hits over six innings while striking out six and walking three.
Martin delivered the big blow off Miller, a two-run double in the sixth, and threw out two Atlanta baserunners to delight the Rogers Centre gathering of 44,794. The Jays lost leadoff hitter Devon Travis (left rib contusion) in the first.
Hit by a pitch, Travis left after diving back to first on a pickoff and was replaced by Steve Tolleson. Travis is listed as day to day.
After Freeman scored in the third, Gomes' sacrifice fly brought Chris Johnson home and chased Norris, who was replaced by right-hander Marco Estrada.
Martin brought Jose Bautista (walk) and Edwin Encarnacion (single) home in the sixth. But after walking Justin Smoak, Miller retired Kevin Pillar (flyout) to end the threat.
"He's a tough assignment," Gibbons said of Miller.
Left-hander Andrew McKirahan replaced Miller to start the seventh and retired the two batters he faced before right-hander Cody Martin came on. Right-hander Jason Grilli retired the three Toronto hitters he faced in the ninth for his sixth save.