BALTIMORE -- There seems to be no end to the list of players capable of carrying the Baltimore Orioles to victory this season.
Nick Markakis led off with a homer on a 0-2 pitch before Adam Jones singled and took third on a single by Chris Davis. Valverde (0-1) then retired Matt Wieters and J.J. Hardy on popups before Dickerson hit a 2-1 pitch into the bleachers in right-center, much to the delight of the sellout crowd of 46,249.
Dickerson was making his first start since May 23 after a bout with a sore wrist. Batting eighth in the lineup, he was 0-for-3 with two strikeouts before connecting.
"It's an amazing feeling, just to contribute in such a big situation," Dickerson said. "This team just claws back every single time. I'm just so happy I could cap it off for them."
He never before hit a game-ending home run at any level.
"I knew right away," Dickerson said. "It was awesome. That's the type of feeling you just want to bottle up and take home forever. First walk-off at any level. Just an incredible feeling, an incredible moment."
"That says a lot about our ballclub, up and down the lineup," Markakis said. "Anybody can hurt you. I think that's a positive thing we've got going for us right now."
Manager Buck Showalter said, "It's not like one guy's got to carry the load."
Darren O'Day (3-0) got the final out in the ninth for the Orioles, who have won eight of 11.
This one hurt more than most.
"We obviously let one get away," manager Jim Leyland said. "Scherzer got us where we wanted to be and then we just didn't close it out. Scherzer was spent and that was going to be his last inning. His pitch count was getting up there pretty good. It was no brainer to bring in Valverde."
After yielding a third-inning home run to Jones, Scherzer didn't allow another runner to reach and was poised to become the first Detroit pitcher to start a season 8-0 since Jeremy Bonderman in 2007.
The right-hander struck out 10 and walked two, but he threw a season-high 119 pitches before being replaced by Valverde, who came to the mound with a 0.75 ERA.
He walked off with his first loss and a 3.55 ERA.
"I miss a couple of pitches," Valverde said. "They have some good hitters. Tomorrow is going to be a new day. I had a tough day. There's nothing I can do. I feel bad for Max because he threw a good game."
Orioles starter Miguel Gonzalez allowed a season-high five earned runs over six innings and allowed both Detroit homers.
The Tigers went up 2-0 in the first inning when Andy Dirks singled and Cabrera hit his 16th homer of the season. He's the first Detroit player to hit 12 homers in May since Willie Horton in 1968.
Baltimore got a run back in the second, getting singles from Jones and Davis before Wieters delivered a sacrifice fly. In the third, Markakis walked before Jones connected to give the Orioles a brief 3-2 lead.
A two-out RBI single by Garcia tied it in the fourth, and Detroit went up 4-3 in the fifth when Dirks and Cabrera singled ahead of a run-scoring grounder by Victor Martinez.
Garcia hit his second homer of the season for a 5-3 lead in the sixth.
Cabrera went 2 for 5 with a walk and took over the AL lead in hits with 81. He began the game tied with Machado, who was held hitless. ... Orioles RHP Pedro Strop, who's been on the DL since May 25 with a lower back strain, is slated to throw a simulated game Saturday. ... Justin Verlander takes the mound for Detroit on Saturday. The Orioles will start Jason Hammel, who's 7-2 overall but 1-2 with a 6.38 ERA at home.