Chad Kuhl - Chad Kuhl is going to miss the 2019 season, as he had surgery very late in the 2018 season. Kuhl had started to figure things out with a higher usage of his slider, and as we have seen in the past with heavy slider usage arms, they usually have arm troubles. The Pirates have enough depth to get over Kuhl’s missed season, as he was a backend rotation arm, but still any starting pitcher injury is a struggle to overcome.
Joe Musgrove - Joe Musgrove has been dealing with injuries in his career, and is going in for surgery again, this time due to an abdominal issue. It will be extremely close for Musgrove to return for a full Spring Training, so some rehabbing time might be in line for him as the season opens up. With Kuhl already ruled out for the year, another arm down would not be good for the Pirates.
Gregory Polanco - Gregory Polanco wend down with a dislocated shoulder late in the year, and this is going to leave him missing the early part of the season for 2019. This is a big lefty power bat out of the order, and Polanco is one who needs to establish himself as someone the Pirates can build around for the next few seasons. Polanco has generally been healthy, but lingering injuries have slowed him down at times.
Over the last few decades the Pirates have been bad more often than not, and injuries to younger prospects or signed veterans have been a part of the reasoning. In the early 2000s you had guys like Pokey Reese and Kris Benson who were both expected to be higher starting players go down with major injuries. While the injuries are not quite to blame for their progress in the majors, they certainly didn’t help. Moving forward a bit, World Series hero Steve Pearce was drafted by Pittsburgh and landed on the DL multiple times with injuries. The bigger one was the torn calf in 2011.
Charlie Morton was not the arm you know in Houston, as he struggled greatly in Pittsburgh. He ended up having Tommy John surgery, which actually may have added some velocity to his game as he moved away from Pittsburgh. Jung Ho Kang had shown some power during his short stint with Pittsburgh, but the major leg injury breaking his tibia and tearing an MCL. Kang also had major off the field issues that caused him to miss even more time.