We’ve caught our breath from the busiest Trade Deadline in history, and we know who made the most aggressive upgrades. The already impossbily stacked Dodgers now have Max Scherzer and Trea Turner. The Giants might have filled multiple holes by acquiring the versatile Kris Bryant. The Blue Jays’ rotation looks a lot better with José Berríos. The White Sox somehow have both Liam Hendriks and Craig Kimbrel now to shorten games.

But even after 149 players switched uniforms across 56 trades between July 15-30, not every contender’s needs could be addressed. That could create some lingering regrets about what more could have been done.

As we turn our attention toward the stretch run, here’s a look at the biggest perceived holes on postseason contenders that weren’t significantly addressed at the Deadline, and how those contenders hope those questions get answered between now and the Oct. 3 regular-season finale.

Boston Red Sox
Biggest remaining question: Starting rotation

The Red Sox were linked to Scherzer in rumors, sparking dreams of an incredible tandem of Mad Max and Chris Sale atop the rotation, but Boston stood pat with its rotation. If Sale’s return from Tommy John surgery goes anything other than “as smooth as possible,” it’s an open question whether this group is deep enough for October. Nathan Eovaldi is the only current Boston rotation regular with an ERA under 4.00, with Eduardo Rodriguez suffering through a strange, snake-bitten season and Garrett Richards struggling after MLB installed tougher mound substance restrictions.

This unit has been getting by while the offense and bullpen thrive, but one wonders if the front office put too much pressure on Sale to carry it the rest of the way. After the Blue Jays, Rays and Yankees all made major Deadline additions, the Red Sox will have to figure out how to make their rotation work.

Best-case scenario: Sale doesn’t suffer any hiccups upon return, giving Boston the fortifying ace it needs. Rodriguez’s ERA drops closer to his more encouraging peripherals.

Houston Astros
Biggest remaining question: Center field

Houston doesn’t have many holes, and its bullpen looks improved with the additions of Yimi García, Kendall Graveman, Phil Maton and Rafael Montero. One area that many thought the Astros might attack was center field (a perceived hole dating back to free agency), but they actually traded away starting center fielder Myles Straw to Cleveland to get Maton.

That gave Houston’s center-field job to Chas McCormick with all of 65 big league games under his belt. While McCormick is far from a household name, the Astros likely recognized some tools in their rookie outfielder that made it worth the gamble. McCormick owned a 113 weighted runs created plus (wRC+) when Straw was traded away, and his Statcast peripherals are more impressive. Entering Wednesday, he was among the top 10% of qualified players in average sprint speed (28.9 feet per second), had already accumulated 6 Outs Above Average in only 64 games (40 starts) in the outfield and had homered 10 times in 164 at-bats with strong barrel (10.7%) and hard-hit (49.1%) rates.

Best-case scenario: The Astros’ faith in their toolsy young center fielder pays off as McCormick steps up as an all-around contributor.

New York Mets
Biggest remaining question: Starting rotation

Credit where credit is due: The Mets added two starters in Rich Hill and Trevor Williams. But news of Jacob deGrom’s most recent setback that sidelines him until September (coming mere hours after the Trade Deadline) only reinforced the hard lesson that the Amazin’s have learned all season: A team can truly never have enough starters.

The 41-year-old Hill has put up mixed results in his first two starts in Queens, and his career history with injuries always brings question marks. Williams was excellent for the Pirates in 2018 (3.11 ERA), but he has struggled (5.48 ERA) ever since, leaving the question of whether his quantity of innings comes with enough quality.

Carlos Carrasco became the 17th Mets pitcher to start a game this year when he made his season debut last Friday, the most used before August by any National League team in history. Can Carrasco’s troublesome right hamstring hold up? Can deGrom come back at full strength? Will the Mets regret not meeting the Twins’ asking price for Berríos? Given all the twists and turns in the Mets’ pitching staff to this point, it’s an open question of whether they have enough arms left to get to the finish line.

Best-case scenario: deGrom comes back healthy. Carrasco gives New York a solid top four alongside Marcus Stroman and Taijuan Walker. Noah Syndergaard (who likely won’t have enough time to stretch out as a starter when he returns from Tommy John surgery) shines as an overqualified swingman.

San Diego Padres
Biggest remaining question: Starting rotation

Somehow, after all the renovations the Padres had done to their rotation across the last year, that unit was still the biggest flashing light on the dashboard entering the Deadline. One can’t fault general manager A.J. Preller for trying (the Friars seemingly had Max Scherzer, until all of a sudden they didn’t), but it’s still stunning that San Diego walked away without adding a single impact starter.

On one hand, Padres fans could look at Yu Darvish, Chris Paddack and Blake Snell all carrying ERAs of 4.78 or higher between June 1 and the Deadline and bemoan Preller not adding a starter (Paddack also strained his left oblique just after the Deadline passed). But they could also look at the talent level there (along with Joe Musgrove, who was an NL Cy Young Award contender alongside Darvish through the end of May) and figure better times are ahead.

“Snell will tell us how our season ends,” a Padres official told MLB.com’s AJ Cassavell after Friday’s Deadline, and one would think, given his prior form, that he can’t continue to pitch this poorly. Regardless, San Diego needs more from this group: Its resilient relievers entered Wednesday with MLB’s best bullpen ERA (2.87), but it also had pitched the second-most innings behind the Rays.

Best-case scenario: The Padres’ big-name starters rediscover their form and reward Preller for his faith, taking innings off the Friars’ bullpen.

Los Angeles Dodgers
Biggest remaining question: Bullpen

The defending World Series champs have a genuine embarrassment of riches in the rotation and the lineup after adding Scherzer and Turner, and even their bullpen (which entered Wednesday with a top-10 ERA across the Majors) looks solid. But there might be cracks forming there. Kenley Jansen had a string of three straight blowups in July, earning him some rare boos at Dodger Stadium. Jimmy Nelson has been a revelation, but he’s also throwing more innings than he has since 2017 (and was placed on the injured list on Wednesday with right elbow inflammation). Brusdar Graterol has all the stuff in the world, but he’s showing rust since coming off the injured list.

One reason the Dodgers aren’t running away with the NL West (besides the Giants playing so well) is their bizarre funk in extra-innings games. L.A. entered Wednesday 1-11 in games that went to extras and had lost its last 10 such contests. Dodgers relievers had given up a run in each of the club’s past 13 individual innings past the ninth. Much of those struggles are obviously fluky, but it does make one wonder if the Dodgers -- who were heavily rumored in connection with Kimbrel -- could have used an impact arm for their ‘pen.

Best-case scenario: Jansen, who has overcome plenty of ruts before, gets locked back in. Nelson’s resurgence continues and Graterol pitches to his talent level, giving the Dodgers a lockdown back end with those three and Blake Treinen.

Seattle Mariners
Biggest remaining question: Impact bat

General manager Jerry Dipoto, true to form, kept us guessing by trading away one closer in Graveman and acquiring another one in Diego Castillo. But with the Mariners surprising the baseball world by being as close to the AL’s second Wild Card spot as they are, they didn’t do much to improve a somewhat anemic offense. Dipoto is high on the one bat he did add in Abraham Toro, but it’s a lot more faith placed in Toro’s Minor League resume (.836 OPS across 377 games) than his small sample in the Majors (.694, entering Wednesday).

Toro positively raked in his first week with Seattle, and with the 2021 Mariners toting a negative run differential, there were good reasons for Dipoto to protect prospects for better Seattle clubs in the future. But one wonders about the effect on clubhouse morale after not adding a little more to a team that rolled into the Deadline.

Best-case scenario: Seattle continues to defy that negative run differential, and Toro continues as an impact bat to reward Dipoto’s confidence.

Philadelphia Phillies
Biggest remaining question: Center field

The Phillies, despite their uninspiring performance so far, are cutting down the Mets’ lead in the NL East. President of baseball operations Dave Dombrowski operated in his familiar buyer’s role at the Deadline, but he made his biggest move addressing a rotation he was already publicly confident in by trading for Kyle Gibson. That means the Phillies’ roster still, somewhat shockingly, features a heavy dose of Odúbel Herrera (who hasn’t posted an above-average OPS since 2017) in center field. Championship teams are generally strong up the middle, but the Phillies still have arguably the biggest center-field hole of any team still in the hunt.

Best-case scenario: Gibson and Ian Kennedy bolsters the pitching staff, and Bryce Harper and the rest of the Phillies' lineup mashes enough to mask the hole still left in center. Herrera, for what it’s worth, got off to a strong start to August.