What Shape Might The Padres' Bullpen Take In Cubs Series?

In terms of the total body of work, no team in Major League Baseball has a better bullpen than the San Diego Padres. It's a group that sits atop the league in fWAR (7.6), ERA (3.06), and strand rate (77.3%), while ranking second in FIP (3.53) and third in strikeout rate (25.8%). With a playoff series against the Chicago Cubs now directly on the horizon, the calculus changes a bit for this group. Or does it? 

We do know some things about the shape of the Padres' relief corps as the postseason gets underway. For example, we know it's a group that will be without Jason Adam for the remainder of 2025 after a ruptured quad ended his season. We also know that it'll be Robert Suarez in any save situation. Despite questions about Mason Miller's role following his acquisition, Suárez has still been clinging to ninth-inning duty. It's hard to imagine that changes now. 

How the rest transpires is anyone's guess. We know that each of Miller, Adrian Morejon, and Jeremiah Estrada will be leaned on heavily. David Morgan or Wandy Peralta could get some bridge work in the middle innings. If Mike Shildt is hard-pressed for a lefty while saving Morejon for higher leverage, we'll probably see Yuki Matsui in the mix as well. That's the group overall, though: Suárez, Miller, Morejon, Estrada, Morgan, Peralta, and Matsui. How each arm will respectively be deployed will depend heavily on Craig Counsell's lineup on the other side, though. 

In that vein, it's very possible that we'll see a lineup similar to the one the Cubs fielded on Saturday. That went as such: 

1. Michael Busch (L) - 1B
2. Nico Hoerner (R) - 2B
3. Ian Happ (S) - LF
4. Kyle Tucker (L) - DH
5. Seiya Suzuki (R) - RF
6. Carson Kelly (R) - C
7. Pete Crow-Armstrong (L) - CF
8. Dansby Swanson (R) - SS
9. Matt Shaw (R) - 3B

That the Padres will likely roll out exclusively right-handed starters in some form leaves the above as close a configuration as possible to the one we'll see, with Tucker possessing the chance to move back into right field. In contrast, Suzuki moves back to the designated hitter spot. Regardless of that nuance, it remains a tricky lineup for Shildt to navigate in the bullpen game. 

Left-handed hitters are strategically placed within that lineup, and each one possesses the ability to create impact at the plate. Each of Busch & Crow-Armstrong reached the 30-homer mark during the regular season, and injuries don't necessarily detract from the elite hitter status that Tucker has maintained for the last handful of years. That creates a challenge in itself. Because while Busch (81 wRC+), Crow-Armstrong (59 wRC+), and Ian Happ (92 wRC+) have struggled against left-handed pitching, the rest of the lineup is comfortably above average versus southpaws this year. To say nothing of the fact that the Padres' left-handed offerings are minimal. 

Yuki Matsui has pretty dramatic reverse splits this year, with a .366 wOBA allowed versus lefty hitters against a .283 figure versus righties. That limits Shildt's options to essentially Adrian Morejon in attempting to isolate lefty-lefty matchups. But even with Morejon's dominance this year, the fact that he's still a largely contact-oriented arm (even against type) means that we might not see too much right-handed opposition for him. He will, nevertheless, be heavily utilized in those matchups as much as possible, with the chance to oppose a softer-hitting right-hander like Dansby Swanson or even Nico Hoerner existing as a possible opportunity for him to stretch his legs a bit.

The other arm that could serve as an option for the Cubs' challenging left-handed hitters is Jeremiah Estrada. Like Matsui, Estrada is working with reverse splits that include a .317 wOBA allowed against right-handed hitters and a .264 mark against lefties. He's endured a challenging second half, but the body of work being strong against lefties and adequate against righties does allow for the greatest possibility of overlap among the Padres' relief arms. 

Where Mason Miller could factor in begins in the fifth spot in the lineup. Even with decent splits, it's likely that the Padres would want to avoid their right-handed fireballer against an upper half that leans 75% left-handed (Busch, Happ, and Tucker). Instead, working him in against the path of Suzuki, Kelly, Crow-Armstrong, Swanson, and Busch could be an efficient way of managing outs in the later innings. In that case, you're not only getting Miller against a predominantly right-handed group, but Crow-Armstrong has a Run Value of -3 and a strikeout rate near 35 percent against four-seam fastballs in 2025. That aspect provides a lot of runway for an arm that has otherwise allowed a .172 wOBA against righties this season.

It's Miller's involvement that really helps to develop a clear picture of how this bullpen could take shape if you're content to let Miller loose against the fifth through ninth hitters in the lineup to preserve matchups, which allows you to work Morejon and Estrada against the upper half. Factor in Suárez in the ninth and you're, ideally, speaking for at least four innings of a game. Maybe more. Especially when you consider the David Morgan of it all.

Morgan, in particular, is something of a wild card within the group as he's pitched to a 2.66 ERA and 25.9 percent strikeout rate. There have been some command issues (11.9 BB%), but he's also someone who can offer up success against right-handed hitting in a pinch. Or serve as a bridge before you reach the higher-leverage arms. Either way, the additional presence of Morgan's 2025 success opens up the innings coverage to potentially five or even six, depending on the starters' output. Factor in Matsui & Wandy Peralta as guys capable of getting you to the next one, and there's a lot of length here even in Adam's absence.

In any case, though, it's a group that stands to get a great deal of work over the next three days. The rotation is, in itself, a bit of an unknown in the volume game, given their 18th-ranked innings per start (5.09). If a starter is struggling to get through the early innings, an occurrence that has become too frequent for Padre starters, and you combine that with the upside that the relief arms offer, it's hard to imagine Mike Shildt being too hesitant to get his bullpen active at Wrigley Field this week.