In his second outing since coming off the disabled list, Wells gave up five runs and seven hits in 6 1/3 innings Tuesday night as the Red Sox lost to the Toronto Blue Jays 9-6.
In his first start after a trip to the disabled list, Wells gave up seven runs in 1 1/3 innings at Oakland on May 18. He has a 6.81 ERA.
"Eventually, it's got to turn around. If it doesn't, you know what? I don't expect to be here if I keep pitching like this," Wells said. "Giving up five runs a game is getting more and more discouraging."
The 42-year-old left-hander blew a 3-0 lead in the fourth as Toronto rallied with four runs.
"Besides that one inning he was very good," Boston manager Terry Francona said. "He made mistakes, and he paid for it."
Reed Johnson homered twice, including a tiebreaking three-run drive in the ninth inning. With the score 6-all, Orlando Hudson singled with one out in the ninth off Alan Embree (1-2), John McDonald walked and Johnson hit Toronto's first game-ending home run of the season.
Johnson, whose two-run homer in the seventh off right-hander Mike Timlin put Toronto ahead 6-5, had the second multihomer game of his career.
He went 2-for-5 with a career-high five RBI, raising his average to .300. Johnson only starts against left-handers, but he's made no secret of his desire to play every day.
"I can't really think about that. In my first couple at-bats I had that in mind," said Johnson, who went hitless in his first three-at bats.
Toronto manager John Gibbons told Johnson to relax halfway through the game.
"I ended up relaxing and putting better swings on the ball," Johnson said.
Miguel Batista (3-0), Toronto's fifth pitcher, threw 1 1/3 hitless innings.
David Ortiz had three RBI for the Red Sox, who started a six-game trip to Toronto and New York. Ortiz hit into a run-scoring double play in the first, then had a two-run single in the third and an RBI single that tied the score 6-all in the eighth.
Blue Jays starter David Bush gave up three runs and five hits in three innings.
Toronto went ahead in the fourth on Aaron Hill's two-run triple and Gregg Zaun's two-run homers. Zaun was activated from the 15-day disabled list before the game after being hospitalized earlier this month with a concussion after breaking up a double play.
Boston's Edgar Renteria, who entered the game in a 2-for-13 slump, led off the eighth with a triple off Jason Frasor before Ortiz's single tied it. With the potential go-ahead run on second with two outs, Batista struck out Jason Varitek.
- Blue Jays ace Roy Halladay will miss his scheduled start Thursday because of a strained muscle on his left side.
- Boston 3B Bill Mueller left the game in the ninth after being hit on the left foot by a pitch. X-rays were negative, and Mueller said he could play Wednesday.
- Wells has allowed 11 earned runs in 12 2/3 innings in two starts against Toronto this season.