CHICAGO — The Minnesota Twins’ pitching puzzle got harder to piece together after Kendry Rojas suffered an elbow injury Thursday.Rated the No. 9 Twins prospect earlier this year, the hard-throwing left-hander was scratched an hour before he was scheduled to start Thursday with left posterior elbow soreness. Rojas, who struck out 14 batters and posted a 1.26 ERA in 14 1/3 innings, flew back to Minneapolis and is scheduled to undergo an MRI on Friday, Twins manager Derek Shelton said.Already without Pablo López and Mick Abel, and with several other starters’ workloads being monitored, potentially losing Rojas would put a serious strain on the team’s resources. The Twins then got a sense of how difficult life without Rojas can be when Simeon Woods Richardson filled in for the injured pitcher and surrendered five earned runs over 2 2/3 innings in a 6-2 loss to the Chicago White Sox at Rate Field.“We did not feel it was responsible at all to pitch (Rojas),” Shelton said. “It’s tough. … We’ll have to see. Don’t want to speculate. We’ll have to see what we’re doing and then go from there.”Even after dropping three of four games to a surprisingly good White Sox team this week, the Twins are still mostly playing competitive baseball. The team sits 27-30, on pace for 77 victories, and is battling for the final Wild Card spot in a watered-down American League.The team’s projected win total is ahead of what oddsmakers thought the Twins would do this season by nearly five victories. Still, one reason the Twins are playing better than expected is their ability to withstand myriad injuries and underperformance in the starting rotation.Adding Rojas to the injured list could crash the whole system.Seven games into a stretch of 17 in a row, the Twins already are focused on monitoring the workloads of rookie Connor Prielipp and fellow starter Taj Bradley.