Brad Penner and Kirby Lee-Imagn Images

Plan A for Chicago’s starting rotation went out the window all the way back on April 4 when Cade Horton went down with a forearm strain. After he’d finished second in Rookie of the Year voting in 2025, the Cubs were counting on him as a key contributor in 2026. Instead, his season ended after just two starts. Then on April 6, Matthew Boyd hit the IL with a bicep strain. Fortunately, he was only sidelined for two weeks, but by May 6 he was out of commission again, this time with a meniscus tear that took him out until June 25. Offseason rotation addition Edward Cabrera has also logged multiple IL stints this year — first, a blister that sidelined him from May 24 to June 5, then a hamstring strain that has had him on the shelf since June 24. Strained hamstrings aren’t contagious, but if they were, Cabrera would’ve caught his from Jameson Taillon, who was out with the same injury from June 9 to July 20 and then designated for assignment a week following his return due to poor performance. Given the myriad of injured starters, by early May the Cubs were forced to move Ben Brown from his long-relief role in the bullpen back to the starting rotation. He made eight starts before landing on the IL with a neck strain.

After placing both Cabrera and Brown on the IL on June 24, the Cubs started their deadline shopping a little early, trading with the Mets for left-handed starter David Peterson on June 25. Peterson has not pitched well this season, posting a 5.52 ERA and a 4.11 FIP over 101 innings, but aside from one clunker against the Cardinals, his results have been much better with the Cubs. Over his last four starts, he’s pitched to a 1.52 ERA, albeit with a 4.20 FIP. Nevertheless, Peterson does not single-handedly fix the Cubs’ rotation, nor does Kevin Gausman, whom they acquired from the Blue Jays on Sunday. No, and even with Cabrera pitching in his first Triple-A rehab game last Friday (1 2/3 IP, 3 ER, 2 BB, 3 K), it’s always a good idea to go ahead and add one more guy. Maybe even two.

Thus, in the hours before the trade deadline on Monday, the Cubs linked up with the Mets once more, this time agreeing to send infield prospect Jefferson Rojas to New York in exchange for right-handed starting pitcher Clay Holmes and outfielder Tyrone Taylor. But that’s not all, as Chicago also acquired right-handed reliever Ryan Zeferjahn from the Angels in exchange for catcher/DH Moisés Ballestero and right-handed pitcher Mason McGwire. To cap it off, the Cubs sealed a swap with the Marlins in which they sent infielder Jonathon Long and pitcher Jace Beck to Miami for pitcher lefty Braxton Garrett.

Starting with the Mets’ return for Holmes and Taylor, Rojas was the top-ranked prospect in the Cubs system. He placed 47th on the recently updated Top 100 Prospects list. He projects as a big league regular who hits for both contact and power, and though the future projection on both tools is roughly average, he gets a boost from his plus plate discipline. Reports indicate he defends well enough to stick at shortstop, but he has been taking reps at third, since he would have been blocked by Dansby Swanson in Chicago. That works out well for the Mets, since Francisco Lindor is penciled in at short for the foreseeable future.

On the Cubs’ side of the trade, Holmes is obviously the headliner, but as Taylor is the only position player the Cubs added at the deadline, let’s go ahead and tackle that piece first, and then we can fully lock in on the pitching. A true rental, Taylor hits free agency at the end of this season. At age 32, he has thus far posted a career-best 117 wRC+. His bat speed is up almost two ticks, and after employing a somewhat flatter swing last season, he’s returned to a more uppercut stroke this year. Along with the added bat speed, a slight shift back in the box seems to have improved his timing. The tweaks to his mechanics have unlocked a greater ability to pull the ball in the air, which tends to correlate with increased production overall.

Taylor’s defense has taken a step backward this year according to the metrics, but his arm strength and sprint speed remain well above average, suggesting a bounce back is possible. And though he’s been below average when playing in center and right, he’s been better in left field, which is where he’s mostly likely to play in Chicago. In splitting fourth-outfielder duties with Michael Conforto, Taylor’s largest value add will be spelling Ian Happ in left field when the team is facing a left-handed starter. Happ, a switch-hitter, has posted a 48 wRC+ against southpaws this season, compared to Taylor’s 146 wRC+.

As for Holmes, Chicago’s newest starter is on a rehab assignment as he works his way back from a fractured fibula sustained in mid-May, when a low liner traveling 111.1 mph off the bat of Yankees outfielder Spencer Jones caught Holmes in the calf. Over three rehab starts, he’s thrown 11 1/3 innings, with five runs allowed, four walks, and eight strikeouts. Though those results are not necessarily dazzling, for the two starts where pitch-tracking data is available, his sinker velocity sat around 93 mph (same as before the injury), and by the second outing, he was back to locating the pitch in the zone 58% of the time (again, same as pre-injury), suggesting he’s on track from a command perspective, as well. The 33-year-old could hit free agency at the conclusion of this season, but his current contract grants him a player-option for 2027, which if picked up, would add $12 million to the Cubs’ payroll for next year.

Before missing time, Holmes was showing improvements following his move to the starting rotation last season for the first time since 2018. So far in 2026, he’s pitched to a 2.39 ERA with a 3.21 FIP over 52 2/3 innings, compared to a 3.53 ERA with a 4.11 FIP over 165 2/3 innings last year. This season, Holmes has ditched his slider in favor of a curveball that spins at the same rate and angle as his sweeper, so the two pitches present themselves similarly to the hitter. But while the sweeper is more inclined to dart glove side, the curveball has more downward bite, so if a hitter guesses one and gets the other, he’ll be the newest resident of Flail City. Subtle changes to his sinker and changeup have created a similar effect on the arm side of his pitch plot. The changeup has a few inches less arm-side run (the sinker a touch more) and slightly more drop, creating more separation between the movement profiles of the two pitches to better keep the hitter off balance. These tweaks to his arsenal could explain the drop in wOBA allowed by his sinker, changeup, and sweeper (see table below), the decrease in contact quality against him this year (lower barrel rate, fewer balls squared up), and his improved HR/FB rate, which is down to 7.1% from 10.5% last season.

In addition to this season’s improvements, Holmes has maintained his 95th-percentile groundball rate (56.0%), which suits the Cubs particularly well given that their infield defense ranks second only to the Cardinals in FRV.

With Holmes in the fold, Gausman, Shota Imanaga, Boyd, and Peterson will likely fill out the rest of the rotation in the short term, freeing up Javier Assad and Colin Rea to take on long-relief roles. The Cubs will need to decide what to do with Peterson once Cabrera returns, and after undergoing elbow surgery last April, Justin Steele is expected back on a big league mound at some point over the next month or so, but he’s most likely to pitch in relief. This type of overcrowding within a pitching staff is what folks in the biz call “a good problem to have.” Especially for a team that’s been white-knuckling it the entire season, and not just in the rotation.

Now, we don’t have the time or page space to recap everything that’s gone on in the Chicago bullpen this year, just know that once you get past Jacob Webb, Caleb Thielbar, Trent Thornton, and Ryan Rolison, it’s a whole lot of guys with stuff like, “Acquired from X for cash” and “Claimed off waivers from Y” next to their names in the transaction log. Naturally, injuries have played a role here as well. Daniel Palencia has missed significant time, first with an oblique strain, and now with elbow inflammation. Hunter Harvey has been out since mid-April with inflamed triceps. Phil Maton has twice attempted to come back from tendinitis in his right knee, only to find himself back on the IL a couple weeks later. Hoby Milner has missed the last month and change due to appendicitis. Thielbar missed a few weeks back in May with a hamstring strain. With such a high rate of attrition in the bullpen, the Cubs have found themselves doling out innings to the likes of Aaron Bummer and 2026 Vince Velasquez (who I didn’t know was still pitching until the Cubs announced the roster move). Even with Palencia, Milner, and Harvey throwing again and on track to return before too much longer, the Cubs made the correct decision to bring in reinforcements anyway.

For his part, Zeferjahn has been astonishingly healthy over his pro career, logging just two IL stints, neither of which impacted his throwing arm. With just over one year of service time, the 28-year-old doesn’t hit free agency until after the 2030 season. Zeferjahn debuted in late 2024, making this his second full season in the majors. Thus far in 2026, he’s pitched to a 3.66 ERA with a 3.77 FIP over 51 2/3 innings. Those numbers are a tad higher than preferred for a reliever, but it’s not hard to see the potential upside. He has posted a 33.5% strikeout rate this season, putting him in the 97th percentile in the majors. How does he do it? Well, only two qualified pitchers get more whiffs on their four-seam fastballs (Jacob Misiorowski and Mason Miller), and just three pitchers get more whiffs on their sweepers (Jesús Luzardo, Justin Lawrence, and Gavin Williams). His fastball sits 97 mph, he throws from a relatively low slot (36 degrees), and he gets 6.8 feet of extension (78th percentile) on his pitches, all of which has to make right-handed batters deeply uncomfortable in the box. That effect is reflected in Zeferjahn’s splits, as he’s allowed a meager .261 wOBA to righties, which immediately makes him one of Chicago’s best options out of the ‘pen against them.

To get Zeferjahn, the Cubs parted ways with a pair of 22-year-olds — a hitter who only recently graduated from the top spot in Chicago’s system and a fringy pitcher currently at High-A. After getting the call last season, Ballesteros started 2026 with the big league club, but was optioned to Triple-A in mid-June because it’s tough to contend with a DH who can only muster a 91 wRC+. In his last report as a prospect, both his hit tool and power graded out at 55. Quoting from that report by Eric Longenhagen and James Fegan, “Ballesteros has plus bat speed, above-average raw power, and a knack for hard contact all over the zone.” But not only has his prospect potential not manifested itself at the big league level, since getting sent down, Ballesteros is slashing .235/.347/.353 over 145 plate appearances. It’s definitely far too soon to give up on his potential at the plate, but unfortunately, he is not one of those players who can at least offer some defensive value while figuring things out on offense. Though he came up as a catcher, he’s not really a viable option behind the dish. The trade to the Angels probably opens up an easier path to consistent playing time, but can they offer him the hitting development he needs? The team’s recent track record says no. But hey, with Logan O’Hoppe now with Texas, maybe Ballesteros will get to do some catching after all.

The pitcher headed to the Angels is the son of 12-time All-Star Mark McGwire. He began the season with the Cubs’ A-ball affiliate, pitching to a 2.40 ERA over 30 innings. Mason McGwire was then promoted to High-A, where he’s thrown 29 1/3 innings with a 4.91 ERA. Eric Longenhagen was kind enough to fill me in on the FanGraphs prospect team’s evaluation of McGwire:

McGwire has been up to 99 this season, but he mostly sits 92-96 and attacks the top of the zone. The quality of his fastball’s carry is pretty inconsistent, which is also true for the movement on his breaking pitches — an upper-80s cutter and an upper-70s curveball. To us, he looks like a middle reliever whose fastball will need the extra couple of ticks it would theoretically get in short-relief bursts in order to play like an impact pitch.

The Angels are taking a bit of a flyer on McGwire, but the potential is certainly there.

Last, and also least, the Cubs’ acquisition of Garrett restores some much needed depth within the organization’s pitching ranks. After missing 2025 following UCL surgery in December of 2024, Garrett was healthy entering 2026 and hoping to return to the Marlins’ starting rotation. Instead, he has spent most of the year at Triple-A. He was briefly called up to join the big league club in mid-May, but after two starts, in which he allowed a combined seven runs over 4 1/3 innings, he was sent back down. At Triple-A, he’s posted a 2.90 ERA over 77 2/3 innings, with a 26.4% strikeout rate and an impressive 53% groundball rate. And before getting roughed up in his last two starts, his ERA sat at just 1.52.

According to the Miami Herald, the Marlins ultimately chose to part ways with Garrett due to his resistance to make meaningful changes to his arsenal. Meanwhile, Cubs president of baseball operations Jed Hoyer told reporters that the organization has always liked Garrett, suggesting they’re less likely to want to make dramatic changes to how Garrett operates. If nothing else, the change of scenery, as well as the opportunity to start from a place of positivity, opens the door for a more productive relationship between Garrett and the Cubs’ player development staff. For now, he has already been assigned to Triple-A Iowa, but as Hoyer continued his comments to the media, he said, “We’re going to need depth. We’re going to need innings. He’s likely to provide that here,” before noting that since Garrett has two additional years of team control beyond 2026, the acquisition is, “a future play, as well.”

In exchange for a little over two seasons of Garrett, the Marlins received a pair of low-ceiling upper-minors prospects. Long had a productive year at Triple-A last season, but hasn’t been as impressive in his age-24 season. In their writeup of Long, which was published back in May, Eric and James were skeptical that his swing would translate to the majors. “Long’s swing is, well, long,” they wrote. “It takes a while for his bat to match the pitch plane in a way that enables him to turn on the baseball, and he ends up late to the contact point. Long’s spray profile is super weird, and he ends up tomahawking a lot of high fastballs the other way when he isn’t getting tied up around his hands.” On defense, he’s been logging most of his innings at first base, and is unlikely to accrue much value on that side of the ball, so he’ll need to figure it out at the plate in order to have a shot at sticking in the majors.

Beck started the season pitching at Double-A and posted a 2.87 ERA over 59 2/3 innings, but his first few outings since moving up to Triple-A have not impressed. His ERA is sitting at 6.60 after throwing 15 innings. His most recent report describes the 26-year-old as a “huge-framed righty with plus-plus extension, good carry on mid-upper 90s fastball. Inconsistency with secondaries has prevented one from emerging as a reliable bat-missing weapon. Still starting, likely a reliever in the end, has late-inning upside if the velo ticks up in short stints and it turns into a monster fastball.”

While the Cubs did part ways with two highly rated prospects, they managed to complete an overhaul of their pitching staff to a degree that’s difficult to pull off over the course of a single deadline. And with more reinforcements returning from the IL soon, they should be well-positioned for a postseason push.