A little more than two years removed from Draft day, when the A's plucked him out of Vanderbilt with their first pick (18th overall), Gray gave the club six strong innings in Toronto, allowing just two earned runs on four hits and three walks with five strikeouts.
But he also had two other runs attached to his name by day's end, as one too many defensive miscues contributed to a 5-4 A's defeat, their seventh in the last nine games, to even the four-game set at Rogers Centre.
Oakland's offense was also back to its old ways with runners in scoring position, going just 1-for-10 in those situations, leaving nine on base along the way, including two that reached base with no outs in the ninth.
Following Reddick's leadoff homer off Toronto closer Casey Janssen, Alberto Callaspo kept things going with a base hit, advancing to second on Coco Crisp's bunt single. But pinch-hitter Stephen Vogt's attempt at a sacrifice bunt went awry, as it led to a forceout at third base. Jed Lowrie then flied out to shallow center, and Yoenis Cespedes struck out, pushing the A's out of first place for the first time since July 1.
"We have an opportunity," manager Bob Melvin said, "and we don't execute yet again."
It's becoming a tiring story for the A's, who couldn't prevent Gray from walking away with a loss despite his impressive recovery performance after issuing two walks and a two-run homer to Jose Bautista in the first.
"I thought it went well," Gray said. "Obviously, early, I was missing with my fastball, falling off a little, and I don't know if that's me a little anxious or what, but the longer it went the more comfortable I got. I was able to make my pitches a lot more efficiently a lot more. My fastball stayed down. That's the main thing, which made my curveball better."
"I thought he threw the ball really well," Melvin said. "Maybe his command wasn't there early on, but he figured that out. Really, two of the runs we kind of gave them. We could have played a little cleaner and kept those two off the board."
Derek Norris' passed ball in the second led to the Blue Jays' third run, erasing a 2-2 tie formed in the top half of the inning when Reddick hit a two-run homer off Mark Buehrle.
In the third, Josh Donaldson's throwing error on a potential double-play ball with no outs set up an RBI single from Colby Rasmus to make it 4-2.
"Just a few mishaps here and there that cost us the game," Reddick said. "He had a rough patch in the first inning, but he battled through and kept us in the game, kept it close."
"He's got a great arm," said Toronto manager John Gibbons of Gray. "He's got a chance to be a real good one. He's got an overpowering fastball. He's got a good curveball. The big thing is, once he gains a little more command of those things, he's got a chance to be really good."
Nate Freiman's sixth-inning sacrifice fly cut Toronto's lead to one, but the Blue Jays tacked on an insurance run in the seventh by way of Jose Reyes' solo shot off righty reliever Ryan Cook, who had not allowed a home run in each of his previous 50 innings, dating back to Aug. 4, 2012.
Reddick, meanwhile, is welcoming his reintroduction to the long ball. He has five in two games -- the same number he had all season entering the series.
They're the most in any four-game series in baseball this year, and he's the first A's player to tally as many in a span of two games since Mark McGwire, who accomplished the feat twice.
"I'm putting good swings on the ball and barreling 'em up," Reddick said. "I'm finally getting consistency, and playing in a good ballpark helps.
"It's kind of unbelievable. Definitely going up there today, feeling like I had a shot to hit at least one. After last night I have nothing but confidence out there. I don't know if I look at it as figuring something out. It's just constant work finally paying off. Watching video is finally paying off. Hopefully this is something I can stick with and keep doing the rest of the year."