He'd been so good in six games since returning from Triple-A Charlotte on June 8, but asking for yet another sterling performance from the 37-year-old right-hander on 10 days' rest may have been demanding too much.
Contreras, making his first start since before the All-Star break, looked rusty, lasting just 4 1/3 innings in a 10-2 White Sox loss to the Orioles in the series finale on Sunday afternoon at U.S. Cellular Field.
It was Contreras' shortest outing in his seven games since rejoining the White Sox rotation following a stint in Charlotte. Contreras had opted to be sent down to the Minors to regain his strength and focus after a tough early-season stretch with the big league club. Before Sunday's outing, Contreras sported a slim 2.06 ERA in his six starts since June, striking out 38 batters with six walks.
Against the Orioles, Contreras (4-8) struggled with his command from the outset, walking four batters, hitting two more and throwing two wild pitches. In total, Contreras surrendered five runs (four earned) on five hits and struck out one batter, and the difficulties appeared to rub off on his batterymate, backup catcher Ramon Castro, as well. Castro committed two throwing errors on steal attempts early in the game.
Fitting of Contreras' pitching line, he did not allow a run-scoring hit, as all runs scored against him occurred via a walk or wild pitch.
"Just one of those days," Contreras said through translator Oney Guillen. "Nothing was working. The slider was out of the zone. Didn't have a feel for my forkball. Obviously, I could not locate the fastball. It's just one of those days. You just move on."
Despite walking three batters with one hit batsman in the first four innings, Contreras still entered the fifth with the game tied at 1 thanks to White Sox center fielder Dewayne Wise's home run in the bottom of the third.
"He struggled all day long," White Sox manager Ozzie Guillen said of Contreras. "The first four innings, they should have scored some more runs. They were one hit away from opening it up. But I think maybe because of the All-Star break and that many days off, you get rusty, physically and mentally. The velocity was there. Everything was there. He just couldn't throw strikes."
After retiring Brian Roberts on a flyout to lead off the fifth, Contreras ran into major trouble. He allowed a one-out single to Adam Jones, walked Nick Markakis and surrendered a single to Aubrey Huff to load the bases for Melvin Mora.
White Sox pitching coach Don Cooper came out to settle Contreras down, but it did not seem to help. Two pitches later, Contreras threw his second wild pitch, allowing Jones to score for a 2-1 Orioles lead. Contreras then hit Mora with a pitch to load the bases and end his day after 99 pitches.
"You can tell right away that the majority of the guys in the lineup were waiting him out because he can be awfully tough," Orioles catcher Gregg Zaun said. "If you go out there and you get too aggressive, he'll eat you up with that sinker and the split from the left side. [He] drops down. He's awfully nasty with that sinker. ... A lot of guys [grinded] out a lot of tough at-bats."
Rookie left-hander Aaron Poreda came on in relief of Contreras and promptly walked the only two batters he faced on 10 pitches, handing the Orioles a 4-1 lead. By the time reliever D.J. Carrasco had cleaned up the mess in the fifth, Baltimore held a comfortable 6-1 edge.
That advantage proved more than enough for Orioles starting pitcher Jeremy Guthrie, who allowed two solo home runs and three hits in eight innings pitched.
White Sox second baseman Chris Getz belted the other home run off Guthrie (7-8) with the game already out of reach in the bottom of the eighth. It was Getz's second home run of the season.
Wise's home run ended a 125 at-bat homerless streak dating back to Sept. 19, 2008, when Wise hit two dingers against the Royals.
Wise said it was nice to get that monkey off his back, but he applauded Guthrie's effort.
"I think he was just mixing up his pitches really well," Wise said. "Just kept us off balance. It was just one of those days where you just have to tip your cap to him. He pitched a great game."
If not for the middle-inning relief of Carrasco, the game could have been much worse. Carrasco bailed out the White Sox bullpen, lasting a season-high 3 2/3 innings and allowing two hits while striking out three and walking one.
When he left, however, the White Sox pitching staff struggled once more. Recently acquired reliever Tony Pena entered in the ninth with a 6-2 score and allowed four runs, with three coming on a three-run home run by Zaun to account for the final margin.
Despite the loss, the White Sox (47-44) took two of three games from the Orioles (41-50) and remained 1 1/2 games behind the American League Central-leading Tigers, who fell, 2-1, against the Yankees. Chicago welcomes defending AL champion Tampa Bay at home for a four-game series beginning on Monday.
"I don't expect the team to be maxed out every day," Guillen said. "The thing to me is we won the series, and hopefully we're going to bounce back tomorrow against a good ballclub."
Jesse Temple is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.