What to expect when Giolito joins Padres' rotation

MILWAUKEE -- The Padres’ starting rotation is expected to get a boost this weekend when Lucas Giolito arrives. The veteran right-hander, who signed a deal with San Diego last month, is likely to make his debut against the Mariners in Seattle. His exact start date remains unclear, but it should come Saturday or Sunday.

The San Diego rotation has been hit hard by injuries this season but has remained relatively effective, all things considered. Still, Giolito’s arrival is a major boost. Entering play Thursday, Padres starters had covered 202 total innings on the season, ranking 25th in the Majors.

Giolito is a proven veteran who raises the floor significantly -- and if he performs like he did down the stretch last year, he ought to raise the ceiling as well.

What to expect from Giolito
In 26 starts last season with Boston, Giolito posted a 3.41 ERA. He’d missed the entire ‘24 campaign after undergoing elbow surgery, and he didn’t return to the mound until late April. He struggled a bit upon his return from injury, recording a 6.42 ERA in his first seven starts.

Then? Giolito reeled off a stretch of 19 outings with a 2.51 ERA. If the Padres get that version of Giolito -- the guy who received AL Cy Young votes in three straight seasons from 2019-21 -- their rotation will get a major boost.

For now, it’s probably smart to temper expectations. Giolito signed late and had an awkward buildup to the season. If he struggles early … fair enough. But there’s plenty of reason for optimism. In his final buildup start, he pitched six innings of one-run ball for Double-A San Antonio. The Padres hope Giolito hits the ground running.

Who gives way?
In the rotation? It'll be Matt Waldron. He’s struggled immensely as a starter/bulk guy this season, and on Thursday, manager Craig Stammen announced that Waldron would be moving to the bullpen.

Waldron is out of options. The Padres could've chosen to designate him for assignment. But with a thin assortment of rotation options, San Diego wouldn’t be keen on losing one of its potential starters for, essentially, nothing.

Of course, the Padres’ bullpen is full, too. And it’s thriving. Entering Thursday, no team had posted more fWAR from its relievers than San Diego. Sure, there are some elite back-end arms. But it’s a deep group, too. Bradgley Rodriguez and Ron Marinaccio have been integral. Yuki Matsui has looked sharp since his return from a left groin strain.

When Giolito arrives, the Padres will have 14 pitchers for 13 spots. Something has to give on the roster, and it’s not entirely clear what.

What’s next for the rotation?
Stability? That’s a dangerous thing to forecast.

But for the first time all season, the Padres can feel reasonably comfortable about the back of their rotation. Walker Buehler has found something of a groove. Griffin Canning has returned from injury, albeit to mixed results. (On Thursday, Canning allowed six runs on five hits and tossed 64 pitches over just 1 2/3 innings.)

The Padres could certainly use more high-end starters. That’s where they’re waiting on Nick Pivetta and Joe Musgrove. Neither has a timeline yet to return from right elbow inflammation. Sounds like it might be a while for both.

Which is part of the reason the Giolito addition was so critical. For the Padres to reach their ceiling, they probably need those high-end arms contributing down the stretch. But we’re a long way away from “down the stretch.”

With Giolito and Canning now on board, the floor has been raised. There’s no desperation for Pivetta and Musgrove. If they come back healthy, this could be a very good rotation. For now? It’s adequate. Considering the injury issues they’ve dealt with, the Padres will take adequate.