The Twins rallied in the sixth, making it a three-run game, but they simply couldn't come back from the hole dug by Hernandez.
Minnesota starters have now combined for a Major League-worst 5.25 ERA.
"Our starter just didn't do very well," Gardenhire said. "Our hitters stayed after it. We scored some runs. We stayed in the game. We got within striking distance. We felt like we were swinging good, but unfortunately, when you get behind like that, it's an uphill climb."
Hernandez, who had gone just two innings in his previous start, against the A's, turned in another short one against the Indians, who are now tied with the Rays atop the American League Wild Card standings, ahead of the Rangers. Hernandez gave up six runs on seven hits and a walk to finish his season with a 6.83 ERA in 14 appearances, including 12 starts.
"He had a bad night, and they were all over him from the get-go," Gardenhire said. "It was kind of nonstop, and we had to go to other guys."
Cleveland came out swinging, scoring four runs in the first inning, a rally keyed by four extra-base hits. Jason Kipnis sent home the first run with a triple before scoring on a double by Carlos Santana. Asdrubal Cabrera laced an RBI double of his own and scored on a single by Yan Gomes.
It was more of the same in the second, when Hernandez gave up three more runs. Nick Swisher grounded into a run-scoring double play before Kipnis singled to knock Hernandez from the game. Reliever Shairon Martis entered and promptly gave up a double to Santana and a two-run single to Ryan Raburn to put the Twins in a seven-run hole.
"Whenever he made mistakes, we hammered them," Indians right fielder Drew Stubbs said. "If you look at the second, third, fourth hitters of the game, we're hitting doubles and triples and stuff like that. You don't see that too often, where you get on the board that quick and are putting such good swings on the ball."
The Twins didn't get on the board against Indians right-hander Corey Kluber until the fourth, when Trevor Plouffe provided an RBI single after Ryan Doumit singled and Josmil Pinto was hit by a pitch on his right hand with two outs. Pinto left the game after the inning for precautionary reasons, replaced by Chris Herrmann, but only sustained a bruised right hand.
The Indians added two runs in the top of the fifth against right-hander Liam Hendriks on a bloop two-run single by Mike Aviles that Doumit couldn't handle in shallow right field.
The Twins rallied for two runs in the fifth and three in the sixth to get back into the game. Pedro Florimon crushed a two-run blast off Kluber in the fifth -- his first homer since Aug. 20 -- before sending home another run in the sixth on a groundout with the bases loaded. Alex Presley followed with a two-run single to make it a three-run game, but that was as close as the Twins would get.
The Indians added to their lead with an RBI double by Kipnis off Presley's glove in center field in the eighth inning. Kipnis went 3-for-5 and finished a homer short of the cycle. Cleveland added a two-run homer in the eighth from Stubbs after he appeared to strike out on a checked swing.
Hendriks went 4 2/3 innings, giving up five runs on eight hits, and set a season high for a Twins pitcher this season with eight strikeouts.
"I just used well-located fastballs and mixed it up to make them look even harder," Hendriks said. "That's what was working for me. I was able to locate my fastball and move it in and out."
With the Indians and Rays now sharing the top Wild Card berth, several scenarios can play out over the last two games of the season, especially with the Rangers just one game back. But Indians manager Terry Francona is not worried about how things shake out as long as his team makes the postseason.
"I just want to keep playing," Francona said. "I don't want to go home. I just want to keep playing. I don't care where we play, when we play. I just want to keep playing."