It doesn't have to be debilitating though.
While Musgrove rehabs the inflammation in his right shoulder capsule -- with the hope he'll be able to return by the end of the season -- the Padres will need a collective effort to replace him.
If a few things break their way, they can weather that storm. Here's a look at how:
1. Make use of Nick Martinez's versatility
When he re-signed with the Padres during the offseason, Martinez intended to start. But a need quickly arose at the back end of the bullpen with injuries to Robert Suarez and Drew Pomeranz. So Martinez slid back into a late-inning role.
"Yeah, I like to start," Martinez said recently. "But I like to win more."
The Padres need to use Martinez's versatility to their advantage again. He's proven himself more than capable of sliding between roles in-season.
"It's very unique," manager Bob Melvin said. "A lot of guys really struggle with that. I've had guys in the past that have. You can use it as an excuse, too. ... He doesn't get caught up in that. He just goes out there and pitches, and he does it at a high level whether he's starting or whether he's relieving."
There's a vacancy in the rotation on Tuesday. There's no reason Martinez shouldn't fill it. Suarez is back from injury, and the Padres have since added Scott Barlow to their group of late-inning weapons.
Meanwhile, Martinez pitched three innings on Wednesday in a last-minute spot start, then two more on Saturday. He estimates he'd have about 60 pitches if the team needs it -- and he could build up from there.
2. Let Lugo cook
When the Padres signed Seth Lugo, they thought he had all the requisite tools to thrive as a starting pitcher. They were right.
San Diego also figured it probably has to limit Lugo's innings down the stretch, moving him to the bullpen. The club might end up being wrong about that.
Lugo, who starts Monday's series finale against the Dodgers, appears to be on a mission to prove anyone who doubts his durability wrong. He's pitched 89 innings -- 12 1/3 shy of his career high. He plans to blow past that mark.
Of course, it might ultimately help that Lugo missed a month with a calf strain, limiting his workload. (He owns a 3.54 ERA this season. But remove the start in which he was injured, and that number is 3.10.)
"As the next couple of weeks go on, we'll have more of a conversation about Seth to the bullpen versus continuing in the rotation," general manager A.J. Preller said. "But it's not a rule that's hard and fast. When we signed Seth, it wasn't: 'You're going to pitch 120 innings as a starter, then go to the 'pen.' It was more: 'Let's get to this point in the season, and we'll have that conversation.'"
3. Welcome Wacha back with a six-man rotation
Needless to say, with Musgrove out, the health of the Padres' remaining starters is paramount. Michael Wacha has missed more than a month with a shoulder injury of his own. But he appears to be nearing a return, having pitched two innings in a rehab start with Triple-A El Paso on Saturday.
"We're just tag-teaming,” Musgrove said in the aftermath of his injury. “I'm tagging him in. He's going to be big for us."
It's unclear whether Wacha would return this weekend against the D-backs or perhaps the following trip through the rotation. But beginning Friday in Arizona, the team embarks on a stretch of 26 games in 27 days. The best way to ensure a healthy rotation throughout might be to use a six-man group. That would mean keeping Lugo in the rotation when Wacha returns, and adding either Martinez permanently -- or Pedro Avila, who pitched 4 2/3 excellent relief innings on Sunday.
If it’s Martinez (the likelier option), the Padres would need to count on the bullpen to hold its own with the trio of Barlow, Suarez and Steven Wilson setting up closer Josh Hader.
In short: Replacing Musgrove will take a total team effort.
"That one definitely hurts," Wacha said of Musgrove’s injury. "A big kick to the stomach. But every team deals with injuries. You've got to have guys step up and be able to fill those voids -- even though it is a big void to fill."