On average, it’s been a terrible year for Adam Dunn of White Sox

It’s been a season for the record books, one that might prompt sympathetic historians to wipe their brows in relief that there actually was a hitter worse than Adam Dunn.

Bill Bergen once batted .139 for the Brooklyn Superbas, surrounded by teammates named Red, Doc and Nap. The year was 1909. No everyday player has fared worse since.

In the live-ball era that started in the 1920s, Rob Deer holds the record for hitting futility among regulars with a .179 average for Detroit in 1991.

Dunn is making an unintended run at those marks. The Chicago White Sox slugger possesses a .167 average after going 0 for 4 Tuesday against the Angels, needing hits in 16 consecutive at-bats just to pass the infamous Mendoza line of .200.

He has never been one to hit for average (career mark: .245), but in his first 10 seasons he produced loads of home runs, runs batted in, strikeouts and walks — enough of the latter to fashion an impressive .375 career on-base percentage.

This year, with 11 homers, 40 RBIs and a .294 OBP in 104 games, only his strikeout total of 151 remains high.

There has been no escaping his ineptitude. Every stop the White Sox make, someone approaches him in the clubhouse to inquire about it.

“People constantly bring it up,” said Dunn, whose lowest average before this season was .215 in 2003. “Guys in here don’t bring it up. I understand it’s the media’s job and things like that, but if it wasn’t for that it would be obviously a lot easier to keep your mind off of.”

Fans tend to not let you forget it when the only thing that has more zeros than your line in a box score is your four-year, $56-million contract. Dunn has been booed routinely at Chicago’s U.S. Cellular Field, where he is batting .158 in his first season with the White Sox.

The designated hitter and first baseman has been a season-long bust, hitting .160 in April, .204 in May, .136 in June, .145 in July and .180 in August. He’s hitting .037 against left-handed pitchers, many of whom posted higher batting averages in interleague play.

Theories abound as to why a player who tallied at least 38 homers and 92 RBIs in every season since 2004 has suddenly failed so miserably. He’s buckled under the pressure of a big contract with a new team. His rhythm was thrown off by an appendectomy in April. He’s had trouble adjusting to American League pitching.

Dunn, 31, doesn’t subscribe to any of them.

“Yeah, there’s been a lot of adjustments,” he said, “but there are a lot of people who have made those adjustments. So I don’t really have anything to put my finger on.”

Dunn remains in the lineup with his team in a pennant race largely because his manager has no better options.

First baseman Paul Konerko has been limited to designated hitter recently because of a sore knee. Catcher A.J. Pierzynski and outfielder Carlos Quentin have been sidelined by injuries, leaving a power void that Manager Ozzie Guillen hopes the left-handed-hitting Dunn can fill over the season’s final five weeks.

“If I have a better choice, I might change my mind,” Guillen said of playing Dunn. “I don’t make out the lineup because of who he is, how much money he makes. I [want] the best guy out there to play.”

Though the numbers might appear to indicate otherwise, Dunn insisted his season is salvageable.

“The ultimate goal is to win,” Dunn said, “and if I can get hot for a month to help this team get to the playoffs and beyond that, it’s a very successful season.”

ben.bolch@latimes.com