The Red Sox’s near-MLB-best starting rotation didn't reach its current heights easily. Boston came into the 2024 season with questions up and down its pitching rotation after trading away Chris Sale and enduring a Spring Training UCL injury to free-agent addition Lucas Giolito.

Nearly two months into the season, the Red Sox’s starting group has been as good as any, posting a 2.98 ERA while striking out 8.44 batters per nine innings and allowing just 0.98 HR/9. It’s been a collective effort, to be sure, with solid contributions from just about every starter that has taken the bump, but two pitchers in particular have led the way.

Tanner Houck and Kutter Crawford, two late-20s right-handers who had trouble finding their footing as starters before 2024, are putting up Cy Young-caliber campaigns in one of the most surprising pitching developments through the first third of the season.

The two have broken out due to a few subtle tweaks to their arsenals, thanks, in part, to new Red Sox pitching coach Andrew Bailey, whose pitching philosophy can be seen across Boston’s staff, but especially in Houck and Crawford.

Through 10 starts, Houck is in the discussion for the title of best pitcher in baseball, and FanGraphs has him as such, valuing him at a league-best 2.2 fWAR through Friday. The 27-year-old, who will face the Brewers on Sunday, came into the season with a refined approach that has paid off, resulting in a 1.94 ERA, 8.58 strikeouts per nine innings and just 1.66 walks per nine -- more than a full walk lower than his career best entering 2024.

After two seasons spent shifting between Boston’s rotation and bullpen, Houck endured a tough 2023 in which he posted a 5.01 ERA over 21 starts and missed two months after being hit in the face by a line drive in June. Houck entered Spring Training with no guarantee of a rotation spot come Opening Day, but a strong showing in camp was a sign of his success to come.

At the heart of Houck's breakout is a simplified approach. He has ditched his four-seam fastball while maintaining his always-nasty secondary pitches and staying in the strike zone in the process. Bailey imported his "fewer fastballs" strategy from the Giants last offseason, and several Red Sox pitchers, including Houck, have taken that philosophy and run with it.

Houck’s four-seamer was ineffective last season, hit for a .325 average and .550 slugging percentage. Houck has moved away from his four-seamer this season, throwing his slider (42.3%), sinker (30.6%) and splitter (22.8%) almost exclusively while mixing in a cutter. Now, every pitch out of Houck’s hand has decent movement to it. The change has resulted in weaker contact (his barrel rate went from 6.6% to 3.9%) and improved his already excellent ground-ball rate (53.3 percent to 56.7 percent).

“The history of baseball suggests that fastballs in general have the most damage attached to them,” Bailey told The Athletic in April. “So, looking at some fastball rates from last year, there’s some low-hanging fruit there and leveraging our weapons that generate weak contact and swing-and-miss more often.”

Houck’s offspeed and breaking stuff hasn’t missed a beat through these changes, too. His sinker is getting eight inches more vertical break than average, while his slider is even better, breaking nine inches more than average. His splitter, which he’s throwing about twice as often as he had throughout his career, has also turned into a plus pitch, dropping 4.5 inches more than average. As mentioned, the command on Houck’s pitches is as good as ever, to boot, resulting in an 88th-percentile walk rate (4.7 percent) heading into Sunday’s start.

“I think it goes back to just not trying to overdo it, not trying to overthrow,” Houck said in April, per The Athletic. “Everyone gets caught up now on velo, and ultimately, sometimes I've just got to check myself and realize that I know if I’m throwing 91 to 95 miles per hour, it’s probably more beneficial because I get the same amount of movement, but I also command it better.”

Crawford, 28, is also enjoying a mid-career breakout, but he’s doing it in a slightly different way than Houck. Even after giving up a season-worst six earned runs over 4 1/3 innings against the Brewers on Friday, Crawford boasts a sparkling 2.89 ERA and 8.81 strikeouts per nine through what’s easily been the best 11-start stretch of his four-year MLB career.

The career arc of Crawford sounds eerily similar to Houck's. Like his rotation-mate, Crawford took some time to earn a spot in the Red Sox’s rotation before finally getting an extended run last June, but a 4.51 ERA over 23 starts didn’t promise him the same role coming into 2024. Still, the door was left open by Giolito's injury.

Crawford has broken out by cutting back on four-seamers in favor of his cutter, throwing both pitches at roughly the same rate this season after using his four-seamer nearly 50 percent more often than his cutter in 2023. But the biggest change in his arsenal is one much more common across the big leagues: The emergence of his sweeper.

Crawford added a sweeper in 2023, mixing it in only 6.7 percent of the time. This season, the pitch has become a big part of how he attacks hitters, throwing it 22 percent of the time as a third weapon to rely on in any given count.

Crawford’s sweeper has essentially replaced his knuckle-curve, which batters hit at a .340 clip last season, as his favorite breaking pitch to throw off his four-seam/cutter-heavy approach. It’s also giving him the side-to-side movement his arsenal lacked pre-2024.

Crawford's new weapon is breaking 13.2 inches away from right-handed batters, easily the most right-to-left break of any pitch throughout his career. The pitch is not only giving hitters a different look -- it has helped Crawford get a ton of outs as well, holding batters to a .232 average and .393 slugging with a 27.9 whiff rate. Bailey has noticed.

“It generates weak contact; it can generate swing and miss,” Bailey told the Boston Globe earlier this month. “It’s been a really productive pitch for our guys. The sweeper plays off his cutter really well.”

The biggest question, of course, is how long they can keep it up. Both pitchers' peripherals suggest that this stretch is no aberration -- Houck’s 2.21 FIP is third among qualified pitchers, while Crawford is a tick behind at 3.07, 19th in the Majors. Both hurlers eclipsed 100 innings pitched for the first time last season, so some wear and tear is expected as their arms build up to a full 30-plus-start campaign.

But even if Crawford and Houck take a step back from their lofty current levels, it’s a win for the Red Sox, who appear to have turned two pitchers who once shuttled between the rotation and 'pen into front-of-the-rotation arms. Makes you wonder how many other pitchers out there are just an adjustment or two away from being in the Cy Young conversation.