PITTSBURGH — The Minnesota Twins are in a dreadful funk with seemingly no end in sight. Bailey Ober’s injury promises to make things only more challenging.Ten games into a stretch of 17 straight, the Twins were crushed Sunday afternoon by the Pittsburgh Pirates, who completed a series sweep with a 9-3 victory at PNC Park.Zebby Matthews was tagged for seven earned runs in a loss that ensured a once-promising trip ended with the Twins losing six of 10 games, including five consecutive defeats.But what’s even more troubling is that before Sunday’s game, the Twins placed Ober on the 15-day injured list with right elbow inflammation. He’s scheduled for an MRI on Monday, and his loss leaves the Twins with four healthy starting pitchers, two of whom are having their workload actively managed.Earlier this week, the Twins placed Kendry Rojas on the IL with left elbow inflammation, and Saturday, they designated struggling pitcher Simeon Woods Richardson for assignment. Besides Rojas and Ober, the Twins are also without starters Pablo López, David Festa and Mick Abel.“That’s five days from now,” Twins manager Derek Shelton responded when asked who would take Ober’s spot in the rotation. “Right now, I’m trying to get through tonight and (Monday). We’ll figure it out as a group with where we’re going to go. … We’ve got seven more (games in a row). We’ve got to figure it out.”There were no easy answers during a 10-game trip that was unkind to Twins starting pitching, a group that entered the trip with the eighth-best starting rotation ERA in the majors (3.67).Even with their previous injuries, and despite Woods Richardson’s struggles, Twins starters held up nicely through the team’s first 50 games as talented arms Matthews, Rojas and rookie Connor Prielipp filled the voids.But since they arrived in Boston on May 22, Twins starters have an 8.31 ERA with 44 earned runs allowed in 47 2/3 innings pitched over 10 games. Only Matthews in his previous start and Joe Ryan on Tuesday completed six innings on the trip, one that began with the Twins winning four of five games and nearly reaching the .500 mark. After Sunday’s loss, the Twins are 27-33 with seven consecutive games upcoming against the Chicago White Sox and Kansas City Royals.Hoping for a lift from Matthews, the Twins once again needed to turn to the bullpen before the end of the fifth inning. Matthews yielded a solo home run to Ryan O’Hearn to start the second inning. Already trailing 2-0, Matthews hit a batter in the third before serving up Nick Gonzales’ first homer of the season.Matthews, who also struck out seven, allowed three of four batters to reach base before exiting with one out in the fifth inning.“When I executed my pitches, I got good results,” Matthews said. “When I left it over the plate or missed my spot a little, they were putting good swings on it. They did that all weekend; they hit the ball well. … A few too many mistake pitches.”The Twins’ margin for error is razor-thin — not that they have had much at any point this season. The only other starting pitchers healthy are Joe Ryan, Prielipp and Taj Bradley.The pressing issue is the Twins are trying to help Prielipp acclimate to a heavier workload by giving him additional days in between starts. With his just coming off the IL, the team has also limited Bradley’s pitch count in his previous two starts.For the time being, game planning promises to be a difficult task.Here are several other observations from a trying weekend in Pittsburgh:• The rotation’s inability to pitch deep into games and Thursday’s injury to Rojas left the Twins with no choice but to designate Woods Richardson for assignment Saturday.“Our bullpen’s been extremely taxed,” Shelton said.Over the past week, Twins relievers have shuttled back and forth between Triple-A St. Paul to provide fresh options. After pitching Wednesday and Thursday, Travis Adams was shipped out Friday for a fresh arm, only to return Sunday morning.Promoted earlier that day, rookie John Klein pitched well in Saturday’s loss, providing a beleaguered pitching staff with two scoreless innings. But with limited options for Sunday, the Twins sent Klein back to St. Paul in favor of rookie Mike Paredes, who was added to the 40-man roster.After Matthews struggled, Paredes filled in nicely despite starting his major-league debut with consecutive walks. Paredes eventually settled in to deliver 3 2/3 innings, retiring nine of the final 11 batters to the joy of more than a dozen family members who took a red-eye from San Diego late Saturday to take in his first big-league game.Were the rotation in a better spot, the Twins could have hidden Woods Richardson in the bullpen a little longer. With his adapting to a new role, the Twins ideally would have used Woods Richardson sparingly.Coming seven days apart, Woods Richardson’s first two bullpen outings were good, his fastball velocity playing up and his splitter looking sharp. But when he was placed in a difficult spot Thursday, filling in for the injured Rojas on an hour’s notice and only three days after his previous outing, Woods Richardson struggled, allowing five earned runs in 2 2/3 innings.Minnesota’s Brooks Lee has been a substantially better hitter on the road this season. (Justin Berl / Getty Images)• With two more homers Sunday, Brooks Lee’s home and road splits are wildly different.Lee is hitting .311/.365/.585 with seven home runs and 24 RBIs in 116 plate appearances on the road. By contrast, Lee is hitting .191/.248/.255 at home with one homer and 10 RBIs in 101 plate appearances.Lee was unaware of the drastic splits until a reporter informed him.“Maybe I see better on the road,” Lee said. “I also think you’re going to get your fourth at-bat a lot of the time because you’re going to hit for nine innings on the road, so I think that’s a big difference, just getting that extra at-bat, maybe getting more comfortable throughout the game. I do feel like later in the game, I’ve done well on the road, so I think that is a big part of it.”Lee generally is a better hitter later in games this season. Entering Sunday, Lee had a .610 OPS in the first three innings of the game. In innings 4-6, Lee carried a .788 OPS. He’s produced a .699 OPS in the seventh through ninth innings while posting a 1.000 OPS in extra innings.Lee’s homers Sunday occurred in the sixth and ninth innings.