Yunel Escobar added a solo drive for Toronto, which leads the majors with 211 homers.
"The only way you're going to have a chance against these guys is you've got to keep the ball in the ballpark," Rangers manager Ron Washington said. "They got seven and six came via the long ball."
Even the seats were no haven on this day. In the seventh, a fan was struck on the right shoulder by a falling metal letter "B" after a foul ball by Jose Bautista hit a sign honoring Jackie Robinson.
The man was treated with ice packs and returned to his seat.
"I was very surprised, because I didn't expect a 'B' to fall on me," said the injured fan, who gave only his first name as Ian and said he was a season-ticket holder from Toronto.
Tommy Hunter (12-3) struggled early as the AL West-leading Rangers lost their fourth straight. Texas has lost six in a row to Toronto since a win on Opening Day, getting outscored 48-24 in that span.
The Rangers left 10 men on base and went 3 for 13 with runners in scoring position.
"We need to start hitting better," infielder Jorge Cantu said. "We haven't been scoring that many runs. We need to find a way to get on base."
Washington said he's seen "a little bit of everything" during the Rangers' poor run.
"One day it might be the pitching, one day it might be the defense, one day it might be us not putting enough runs on the board," Washington said. "We've just got to work our way through this, and we will."
Romero is 2-1 with an 0.92 ERA in four career starts against Texas.
"It's been fun to play behind Ricky," Wells said. "He challenges everybody, he throws strikes, he's been able to have command of some nasty stuff. His ball moves all over the place and he's been able to harness it. He's learning how to pitch in the toughest division in baseball and it's been fun to watch him grow."
Toronto took a 1-0 lead in the second when John Buck struck out on a wild pitch with two outs, allowing him to reach base and letting Wells score from third.
Rangers catcher Taylor Teagarden tried to throw home on the play, but Washington said Teagarden should have gone to first.
"The right play is at first base," Washington said. "You've got Buck up there swinging and missing, the ball's not too far away, [Buck] can't run, it's the third out. You take the easy one."
The Blue Jays broke it open with a five-run third. Dewayne Wise singled, Bautista walked and Wells lined his 25th home run. Lyle Overbay then doubled and Hill connected for a drive to left, his 23rd homer and second in as many days.
Hunter blamed the poor inning on "a couple of cutters than spun" and said he had trouble with the pitch all day.
"It's an effective pitch when it's good, very effective," Hunter said. "They just caught it when it was not good and caught it pretty square."
Toronto has gone deep in eight straight games, hitting 16 homers in that stretch.
Hunter, who had won his previous three starts, allowed seven runs and seven hits in seven innings.
Toronto purchased the contract of RHP Shawn Hill and recalled RHP Robert Ray from Triple-A Las Vegas. Hill will start Thursday, while LHP Marc Rzepczynski moves up to start Wednesday. ... Rangers RHP Scott Feldman, out since Aug. 22 with a sore right knee, is expected to come off the 15-day DL Tuesday to start in place of LHP Cliff Lee (back). ... Texas purchased the contract of INF-OF Esteban German from Triple-A Oklahoma City and designated INF Alex Cora for assignment. ... Hill started despite leaving Sunday's game at New York with a sore right knee. He was replaced by pinch runner John McDonald in the eighth. ... Rangers OF Josh Hamilton (bruised ribs) said he felt better Monday but was not yet ready to return to baseball activities. ... Texas SS Elvis Andrus (right hamstring) will not play before Wednesday and will likely miss the entire four-game series on Toronto's artificial surface, manager Ron Washington said. ... Toronto OF Fred Lewis (right elbow) missed his fourth straight game.