"This is the best Ubaldo has thrown the ball this year," manager Manny Acta said of the former All-Star, who has been wildly erratic since being acquired from Colorado for four players at the July trade deadline a year ago.
Hernandez (3-3) gave up 10 hits and six earned runs in only 3 2/3 innings. He and Jimenez combined for a 34-minute, 59-pitch first inning that ended with Cleveland ahead 4-1.
"Felix just had an off day," Mariners manager Eric Wedge said of the 2010 AL Cy Young winner. "He's human. I think sometimes we forget about that."
Jimenez (4-3) gave up five hits and three runs over six innings. He threw 107 pitches -- 27 in a long first inning -- walked two and struck out four.
"I was able to attack the strike zone better," said Jimenez, who bounced back from giving up seven runs and walking five in only 4 1/3 innings in a loss five days ago to the Red Sox in Boston.
"It's good to come back from a bad outing. It gives me more confidence."
Jimenez has worked with pitching coach Scott Radinsky to regain his form of early 2010, when he pitched a no-hitter and opened the year 15-1 for the Rockies. He has gone 18-23 since.
"It's all about mechanics, and we've been working on it every single day," Jimenez said.
Dustin Ackley had three hits, including a two-run homer, to extend his hitting streak to 12 games for Seattle, which dropped to 1-5 on a 10-game trip. The Mariners are 1-11 away from home since April 28.
"He did a very good job of getting out of that inning," Acta said. "He was in command the whole time, even after those first two guys got on. He threw 16-of-24 first-pitch strikes and looked relaxed."
Catcher Carlos Santana said he visited the mound early to make sure Jimenez did not tighten up.
"I told him something to make him laugh, then said keep the ball down and concentrate," Santana said. "He did."
Choo scored on a passed ball by catcher Jesus Montero, and Kipnis came home on Hafner's hard-hit ball that Ackley turned into a groundout with a diving stop and throw to first.
After Santana walked, he took off for second with two outs and Cabrera on third. Montero threw wildly past third, trying to get Cabrera leaning off the bag. Cabrera scored, and when left fielder Chone Figgins threw the ball back past Montero for another error, Santana also scored to make it 4-1.
The Mariners had gone 10 straight errorless games, one shy of the club record set Aug. 9-21, 1993.
Ackley's two-run homer, his third of the season, got Seattle within 4-3 in the third.
Kipnis, Hafner and Santana all had RBI doubles in the fourth. Michael Brantley singled home Santana to make it 8-3.
It was the second consecutive rocky outing for Hernandez, who April 19 struck out a season-high 12 in eight scoreless innings against Cleveland. On Friday, he allowed four runs and a season-high 11 hits over 6 2/3 innings in a 6-2 loss to the New York Yankees after giving up only four runs in his previous five starts combined.
Seattle LF Mike Carp was a late scratch. He aggravated his right shoulder during pregame warmups. Carp sprained the shoulder in the season opener in Japan and was out four weeks. ... Veteran RHP Jeremy Accardo worked one perfect inning in his Indians debut. He signed a minor-league contract in January and was brought up Monday from Triple-A Columbus. ... Seattle went 0 for 6 with runners in scoring position and is 6 for 78 (.077) in that situation in its last 12 road games. ... Hafner's 193rd homer for the Indians passed Al Rosen for eighth in team history, 21 behind Andre Thornton. ... Choo is 6 for 13 since moving into the leadoff spot. ... SS Brendan Ryan is 0 for 12 on Seattle's trip and in a 5 for 56 (.089) slump. ... Cleveland sent RHP Dan Wheeler outright to Columbus and released RHP Robinson Tejeda from the Triple-A club. ... WR Greg Little and CB Joe Haden of the Cleveland Browns were at the game, and drew cheers when shown on the giant-screen scoreboard.