SAN DIEGO -- The Padres’ rotation, as it approaches the All-Star break, sits in a curious place. Of the five starting pitchers who began the season in that rotation, the three who remain are mostly thriving.

On Wednesday afternoon, Michael King put the finishing touches on his stellar first half with six solid innings in the Padres’ 2-0 loss to Seattle. He struck out nine and allowed only three hits and one earned run. Let down by both his offense and his defense, it was hard to pin any of the blame on King. He shouldered it anyway.

“I want to put up zeros every time,” King said. “It’s still an ‘L’ next to my name. So I’ve got to be better.”

Nonetheless, the Padres’ plan for King has clearly gone smoothly. In his first full season as a starter, he hits the break with a 3.41 ERA, having already passed his career high in innings. The Padres see no signs of King slowing. The same is true of Matt Waldron, who has been a revelation after earning the fifth spot in the rotation during Spring Training.

And while Dylan Cease’s performance has been up and down lately, his dominant stuff remains, as evidenced by his seven excellent frames against Arizona on Sunday. The Padres can feel legitimately good about three-fifths of their starting rotation.

The other two spots? Hoo boy, are there ever question marks:

• Joe Musgrove remains on the 60-day IL as he battles right elbow inflammation and a bone spur.
• Yu Darvish has been on the IL twice already and was recently placed on the restricted list to tend to a personal family matter. Details around his return are unavailable.
• Lately, Randy Vásquez has been serviceable as a fill-in, but he has a 4.66 ERA this season.
• After being hit hard on Tuesday, Adam Mazur’s ERA ballooned to 7.84, and he was subsequently optioned to Triple-A El Paso.
• There are no obvious solutions in the Minors. Right-hander Jhony Brito was recently sent to El Paso to be stretched toward a starter’s workload, and he’s allowed nine runs in five innings over two starts.

The Padres’ decision to option Mazur was sensible enough. He’s struggling, yes. But more notably, the All-Star break runs next Monday through Thursday, and the Padres have an off-day following their first series of the second half in Cleveland.

“We have an opportunity -- just roster management with the day off tomorrow and the All-Star break coming up -- to just be smart about our roster,” said manager Mike Shildt. “If Maze isn’t going to be getting that opportunity for the next period of time, then we get an extra bullpen arm.”

Left unspoken was the fact that the July 30 Trade Deadline looms. In theory, the Padres only need to use a No. 5 starter once before then. At that point, their rotation could look very different.

Padres general manager A.J. Preller is one of the sport’s most active executives every summer. With his team clinging to the final Wild Card spot in the National League, this year figures to be no different.

“You stay out of a hurricane’s way, right?” Shildt said. “A.J. is a force of nature, and this is his time of year. Draft, Trade Deadline -- this is where he really shines. … I love the club we have. But if A.J. decides to make a move with the club, then clearly we’ll support it.”

Still, in a seller’s market -- with practically every contender searching for pitching -- it won’t be easy to make a meaningful rotation upgrade. Already this season, Preller has parted with a number of the team’s top prospects in deals to acquire Cease and Luis Arraez. It’s worth wondering what’s left to trade.

In the meantime, this relevant bit of news came on Wednesday: Musgrove climbed a mound and threw for the first time since his latest trip to the IL. It wasn’t exactly a bullpen session. He merely played catch from the bullpen mound, introducing the slope into the equation. Still, it’s a notable step toward a potential August return.

“Joe’s one of the best pitchers in the league, so any time you have a chance to add a guy like that, it’s going to be huge,” said catcher Kyle Higashioka.

Without question, a healthy Musgrove would be a notable addition to this rotation for the stretch run. And he might not be the only one.