The good news is that many of the Chicago Cubs' young prospects are showing impressive potential in spring training. The bad news is that their biggest offseason investment could be faced with a setback heading into the 2015 season.

Jon Lester was scratched from his scheduled start on Saturday because of "dead arm," according to Carrie Muskat of MLB.com, but manager Joe Maddon said the ailment will not affect the left-hander's status for Opening Day. While this is common among professional pitchers, it's not the greatest news considering Lester is entering the first season of a six-year, $155 million contract.

"Dead arm" is typically characterized as an overall feeling of fatigue without any identifiable injury.

"More than likely, he will not miss the start after that," Maddon told Gordon Wittenmyer of the Chicago Sun-Times. "But we wanted to be very cautious with him right now ... Guys [on the medical staff] feel really good about it. I checked in with him this morning, and he felt great. We just want to back off a little bit right now."

Lester also told Maddon he experienced "dead arm" before, which is why the team isn't panicking, but the uncertainty that generally surrounds the condition is a reason to be concerned.

"Still, 'dead-arm syndrome' varies so much in its degrees and its causes that even its name 'has become sort of a bucket term,' said Dr. Michael Hausman, the vice-chairman of orthopedics at Mount Sinai Hospital. 'It's not a precise diagnosis,'" via Mike Sielski of the Wall Street Journal.

"These injuries result from a myriad etiologies including compensatory anatomic anomalies that develop in the shoulders of throwers to the repetitive microtrauma caused by years of throwing baseballs," write Dr. Josh Dines and Dr. Rock Positano, both of whom are orthopaedic surgeons specializing in sports medicine. "The end results are injuries that can range from minor strains or tendonitis to complete tears."

While there are physical complications, other medical experts say it can also be mental. Take former Los Angeles Angels team physician Lewis Yocum, for example.

"It's kind of like the 'yips' in golf for some of the guys," he said, via Doug Miller of MLB.com. "You can chalk it up to muscle fatigue or muscle memory fatigue, but a lot of times it might just be a guy over-thinking things."

Whatever the case, pitchers throughout history, especially in recent years, have worked through "dead arm" because it typically goes away most of the time. However, the fact that this is occurring so close to Opening Day isn't the greatest sign for Lester or the Cubs even though he's expected to be fine.

Lester is 0-1 with a 6.48 ERA and 1.44 WHIP in three starts this spring (8 1/3 IP, 11 H, 6 ER).