Kapler said during an appearance on 94 WIP SportsRadio that the starter's elbow "is limiting his ability to get into certain positions," which played a role in his poor first half of the 2019 season:
"He's having a harder time getting extended the way he normally does, especially on that curveball. This is limiting his ability to throw the ball where he wants to throw it. All of that said, Jake is a competitor and for the Phillies, it's always worth considering if Jake at 85 percent of himself is a better option than what we have at Triple-A. It's not terribly uncommon for veteran pitchers to successfully pitch with issues like this one. So as of now, Jake will make his start of us against the [Washington] Nationals and we're going to support him."
Kapler added Arrieta will get "some scans" to help determine the next steps, including whether he'll need surgery to rectify the injury.
Arrieta won the National League Cy Young Award with the Chicago Cubs in 2015, posting a 1.77 ERA and 0.87 WHIP with 236 strikeouts in 229 innings. His numbers have steadily declined since that point, however, including a 4.67 ERA across 18 starts so far in 2019.
"Physically, I'm not in a great spot," he told reporters Saturday. "I think we'll have a better idea over the next couple of days where I'm at."
The Phillies sit third in the NL East with a 47-43 record, 6.5 games behind the division-leading Atlanta Braves. They do own the NL's second wild-card spot, though.
If Philly opts to shut Arrieta down, it would likely turn to prospect Enyel De Los Santos to fill the void behind ace Aaron Nola and Co. in the starting rotation. The 23-year-old Dominican Republic native owns a 3.45 ERA with 52 strikeouts in 47 innings across 10 starts at the Triple-A level this year.
For now, the Phillies are planning to send Arrieta to the mound during their series against the Nats, which kicks off Friday night at Citizens Bank Park.