''I made a mistake by not picking up the third base coach,'' Pillar said after Toronto's 3-2 loss Tuesday night. ''It's as embarrassing as it gets. We are paid to go out there and perform and not make dumb mistakes, especially late in the game.''
Harvey returned to form with seven spotless innings and an RBI double before the Mets held on without their top late relievers - thanks in part to Pillar's baserunning blunder.
Bobby Parnell earned a five-out save in his third outing since Tommy John surgery.
One night after ending Toronto's 11-game winning streak, the NL East leaders rested heavily used closer Jeurys Familia and hard-throwing rookie Hansel Robles. So it was Carlos Torres who entered to start the eighth, and he quickly got in trouble.
Torres issued a leadoff walk and gave up a single to Pillar before former Mets star Jose Reyes singled to right field for his only hit in nine at-bats during his return to Citi Field this week.
Ryan Goins was held at third base - but Pillar didn't realize it. He went tearing around second and, with third already occupied, was a sitting duck to be tagged out after Curtis Granderson's throw was cut off.
''He's was running with his head down and never really looked up,'' Blue Jays manager John Gibbons said. ''We gave them an out right there when we really had them on the ropes. But it's over with and we move on.''
Torres walked Josh Donaldson to load the bases before Parnell gave up a sacrifice fly to Jose Bautista and a run-scoring single to Edwin Encarnacion. But the right-hander, who saved 22 games for the Mets in 2013 before missing the final two months with a herniated disk in his neck, struck out Chris Colabello on a ball in the dirt.
''Sometimes to swim you've got to jump in the deep end, right?'' Parnell said.
In his third outing of the year, Parnell then worked a 1-2-3 ninth for his first save since July 30, 2013. After getting the final out, he breathed a sigh of relief and flashed a smile on the mound.
''That was a big milestone,'' Parnell said. ''Finally had some weight off my shoulders.''
New York won for the fifth time in six games and improved to 11-0 at home against Toronto.
Wilmer Flores and Ruben Tejada each knocked in a run and scored another to help the Mets build a 3-0 cushion. Harvey (7-4), who was 1-3 with a 7.20 ERA in his previous four starts, allowed four hits against the best offense in baseball and gave a huge fist pump after working a perfect seventh.
The ace right-hander, also back from Tommy John surgery this season, struck out six, walked none and was lifted after 107 pitches.
''When you run into good pitching, I don't care how good your hitting is,'' Gibbons said. ''That's what happens sometimes. That's some great pitching.''
Flores hit a leadoff double in the second against Scott Copeland (1-1) and scored on Tejada's single. With two outs, Harvey lashed a ringing double to left-center to make it 2-0.
Mets pitchers have 22 hits this season, most of any staff in the majors.
Flores added a sacrifice fly in the third.
Making his second major league start, the 27-year-old Copeland was pulled for a pinch hitter in the fifth.
''Everything was up in the zone a bit and I was just trying to keep the team in the game still,'' he said.
Copeland pitched again in place of right-hander Aaron Sanchez, put on the 15-day disabled list Monday with a mild lat muscle strain.
''He wasn't sharp. I thought the ball was up more. It didn't have that good life that he gets when he's down,'' Gibbons said. ''I don't think it's fair to the kid after two outings to make a judgment on him. ... I think he'll be fine the next go around.''
Blue Jays: Sanchez is likely to miss his next turn on Sunday as well, Gibbons said. ... Rookie 2B Devon Travis (left shoulder) is 0 for 7 with a sacrifice fly in the first two games of his rehab assignment with Double-A New Hampshire. Toronto hopes to get Travis back within a week or so.
Blue Jays: RHP Drew Hutchison (5-1, 5.75 ERA) pitches Wednesday night at home against the Mets.
Mets: LHP Jonathon Niese (3-6, 4.24) is 0-4 with a 6.82 ERA in his past six starts, though he's pitched pretty well the last two times out. In his only previous start against the Blue Jays, Niese gave up eight runs, eight hits and a career-high four homers over three innings in a 14-5 loss at Toronto in May 2012.