SAN DIEGO -- Matt Waldron's rookie season is at a crossroads.

For three-quarters of the year, Waldron was an integral part of the Padres¡¯ rotation. He made the team as the No. 5 starter out of camp. Then he pitched like he belonged somewhere closer to the top. With injuries piling up, Waldron was a stabilizing force.

It was easy to forget he¡¯s still a rookie, mostly because Waldron isn't your average rookie. He's a 27-year-old whose ascent to the big leagues really began when he started throwing his knuckleball. But Waldron is, indeed, still a rookie, who has logged more innings than he's ever thrown as a professional.

It might be catching up to him. Waldron's recent struggles reached another level on Wednesday afternoon. He allowed a whopping 10 runs on 12 hits in the Padres' 11-4 loss to the Twins at Petco Park. He was a far cry from the pitcher who posted a 3.05 ERA over 16 starts from May through early August.

¡°I want to get back to that,¡± Waldron said. ¡°I think the tough thing about this game -- and maybe life, even -- is just when things are negative, it's hard to snap out.¡±

Waldron appeared to lose confidence in his knuckleball, throwing the pitch at a 23% clip, his lowest rate this season. Meanwhile, the Twins were all over Waldron¡¯s fastball, cutter and slider. He surrendered four extra-base hits, including Matt Wallner¡¯s three-run homer during a seven-run fourth inning.

After 4 1/3 innings of hard contact, Waldron exited, having matched a record for runs allowed by a pitcher in a game at Petco Park. (Jered Weaver set the mark in 2017, then Minnesota¡¯s Joe Ryan matched it in ¡¯22.)

¡°Just too much middle, with not as much late movement,¡± Padres manager Mike Shildt said.

The next step for Waldron remains unclear. Randy V¨¢squez pitched on Tuesday for Triple-A El Paso. It¡¯s conceivable the Padres would swap the two. Or maybe they¡¯d let both pitch in a temporary six-man rotation, easing the overall burden with 18 games in 18 days.

¡°I believe I belong on this field,¡± Waldron said. ¡°Obviously, that doesn't show right now, especially on a day like this. Physically, I think I'm capable of getting there. ... I got to go to the drawing board. It's going to take some serious work.¡±

The Padres must figure out whether the May-through-July version of Waldron can still be harnessed. Because, for all of the team¡¯s strengths, rotation depth is not one of them.

Dylan Cease sits atop that rotation. Joe Musgrove is back from an elbow injury and looks like his old self. Michael King has shown no signs of slowing, even though he, like Waldron, has eclipsed his previous high in innings.

Beyond those three? Question marks. There¡¯s no clarity regarding Yu Darvish, who is on the restricted list. Mart¨ªn P¨¦rez has been mostly sharp since joining the Padres, but he owns a 4.67 ERA overall this year and couldn¡¯t complete five innings Tuesday. V¨¢squez and Jhony Brito have fluctuated between Triple-A and the Majors.

Now Waldron has surrendered 22 runs over his past three starts. He¡¯s clearly not the pitcher he was. He also alluded to a bit of arm fatigue, though he was quick to downplay that.

¡°We never feel perfect,¡± Waldron said. ¡°Feeling good is maybe overrated. But I think mentally, just knowing that in the past, I'd never thrown this much, [I¡¯m] getting used to this workload as a whole.

¡°I'm not done yet. Not even close. The fun stuff hasn't even started yet. I just need to get over that hump.¡±

In a sense, these are first-world problems for the Padres. They remain in the midst of one of the best stretches in franchise history. After winning the first two games against Minnesota, they¡¯ve won nine series in 10 and remain squarely in the postseason picture.

They own the sport¡¯s most intimidating bullpen. Their offense mashes. A struggling fifth starter is hardly the worst problem to have.

Still, the postseason and NL West races allow little margin for error. Up next, the Wild Card-chasing Mets visit San Diego for a four-game weekend set.

¡°I wish I absolutely did more than that,¡± Waldron said. ¡°We have a big opportunity coming up against the Mets. [I was] just not reliable. ¡­ I wish I was better.¡±