OWINGS MILLS, Md. — Needing to regroup quickly after a third straight loss to begin the 2015 season, the Ravens returned to practice with a trip to Pittsburgh rapidly approaching on Thursday night. Conducting little more than a walk-through practice on Monday evening, Baltimore was without tight end Crockett Gillmore (calf), wide receiver Breshad Perriman (knee), and defensive end Chris Canty (calf). After making three catches for 40 yards in the first two quarters of Sunday’s 28-24 loss to Cincinnati, Gillmore did not play an offensive snap in the second half, leaving rookies Maxx Williams and Nick Boyle to pick up the slack at the tight end position. It remains unclear whether Gillmore will be able to play on Thursday, but his absence would spell trouble for a passing game struggling to find any consistent production beyond the 36-year-old Steve Smith. Williams and Boyle combined to make five catches for 63 yards against the Bengals. “The biggest thing those guys have to do is just go in and play within themselves,” quarterback Joe Flacco said. “They can’t try to do too much. They just have to catch the ball, run block — do the simple things. When you’re a young