That says a lot about why the A's have lost 10 of their last 13, including the latest 2-1 defeat to the White Sox on Wednesday. Dunn's single kept Oakland ahead until the eighth inning, when a throwing error by Nate Freiman opened the door for a two-run inning, capped by Avisail Garcia's single off Luke Gregerson.
Josh Donaldson and Cespedes were the heart of the Athletics' attack when they went 59-36 in the first half of the season, but general manager Billy Beane wanted more pitching, even after acquiring Jeff Samardzija and Jason Hammel from the Cubs. So he made the unusual move of trading his cleanup hitter.
Given that the Athletics' limited revenue would make it tough to re-sign Cespedes after 2015, it was a reasonable gamble. But at the moment, with Cespedes settling in nicely with the Red Sox (.274, four home runs and 27 RBIs in 37 games), it has become a point of debate.
Even Lester acknowledged this.
"I can't control anything else besides the fifth day, and I try to go out there and do the best that I can," Lester said after a win over the White Sox on Tuesday. "If that means pitching like tonight and people are still talking about Cespedes, then that's what that means. He was a valuable part of this organization and this team. I can't change that."
When asked if the A's are missing Cespedes, manager Bob Melvin said: "In our organization from year to year, we have a lot of turnover. That's the case for the most part here all the time. Now the balance [with that trade] was: do we have enough offense, do we need more pitching? That's what we came to terms with. You get a Jon Lester, then we try to mix and match and pick up the pieces where Ces was. That was the thinking."
Melvin didn't exactly say no.
The knee-jerk conclusion is that Beane overrated his hitters when he decided that Cespedes was expendable. Perhaps that was because he'd just seen them score 64 runs in 11 games before he made the trade.
That's a lot of hitting, isn't it? But look what has happened since Beane traded some of it.
Oakland, which had averaged 5.05 runs per game through July 30, is scoring only 3.7 runs per game since then.
The four guys who have started games in Cespedes' left-field spot (Brandon Moss, Jonny Gomes, Sam Fuld and Craig Gentry) have combined to hit .200 with no home runs and only two extra-base hits in 130 at-bats. The five players who have started in the cleanup spot -- Moss, Gomes, Dunn, Derek Norris and Stephen Vogt -- have hit .206 with only Dunn's two homers in 136 at-bats.
Moss, who was having a good year (he still projects to have 26 homers and 87 RBIs), might have tried to turn it into a great year when Melvin moved him into the cleanup spot after the trade. He's hitting .149 since the trade, including an 0-for-2 off rookie Chris Bassitt before Melvin removed him for a pinch-hitter, Freiman, in the seventh inning Wednesday.
Gomes, who became a cult hero in Boston during the Red Sox's run to the 2013 World Series championship, has hit .273 for the A's, but he has left a small imprint on the Oakland landscape.
Injuries to John Jaso (concussion), Vogt (sprained left ankle) and Gentry (concussion) are also complicating Melvin's thinking as he tries to get the Athletics ready for this weekend's three-game series in Seattle, which carries significant American League Wild Card implications since Oakland is only 1 1/2 games up for the first spot.
Not that the A's can think ahead until Friday. They've got to face Chris Sale on their way out of Chicago, and he is generally about as much fun as a trip to the oral surgeon.
It's time for the A's to put on their hitting shoes. Hopefully, Cespedes didn't hide them in his equipment bag when he headed to Fenway Park.