There are so many factors that can derail a pitcher’s season. Injuries, sloppy defense, bad luck on balls in play, trouble stranding runners, losing feel for a particular pitch -- all of these and more can make it tough for even the most talented arms to get the results they are capable of producing.

But the next year also offers a fresh start and an opportunity to turn the page. That’s what five MLB.com writers had to consider when they were tasked with each selecting a “rebound” pitcher for 2022.

• 5 hitters who could bounce back this season

Eduardo Rodriguez -- LHP, Tigers
Key number: 3.47 expected ERA in 2021

Clearly, the Tigers are in on a Rodriguez rebound, given that they pounced early in the offseason to sign him away from Boston on a five-year contract worth at least $77 million. At first, that sort of commitment might have seemed odd. The lefty didn’t pitch at all in 2020 while recovering from COVID-related myocarditis, and while he returned to make 31 starts in '21, he posted a 4.74 ERA.

Below the surface, though, more advanced metrics tell a different story. Keep in mind that the Red Sox were the worst defensive team in the Majors (by Statcast’s Outs Above Average), something that clearly hurt Rodriguez. Just one example: Opposing batters enjoyed a .316 average on ground balls against him, easily the highest mark for any regular starter and 75 points above the MLB average. That’s one reason why E-Rod’s expected ERA -- which factors in quality of contact, K’s and walks -- was so much shinier than his actual one. Few pitchers dealt with a gap that big in 2021, and he should fare better in ‘22, especially with fellow new Tiger Javier Báez behind him at shortstop. Rodriguez will still be only 29 this season, and he is capable of racking up both K’s and weak contact, so the best may still be yet to come.

-- Andrew Simon

Aaron Nola -- RHP, Phillies
Key number: 1.28-point gap between ERA and expected ERA

Premise: Nola’s 2021 was one of the unluckiest seasons by a pitcher. Ever. Sure, he gave up a few more homers than you’d like -- 26 in 180 2/3 innings -- but there’s just no way his ERA should have been (gasp!) 4.63, which was fifth highest among qualifying arms.

Proof: Let’s focus on two numbers. First, that 4.63 ERA? Among qualifiers to record a strikeout-to-walk ratio of 5.00 or better -- as Nola did with his 223 K's and 39 BB (5.72 K/BB) -- it’s the second highest in history. (The highest, by the way, belongs to Germán Márquez in 2019, when he had a Coors Field-inflated 6.26 ERA at home.) Second? The difference between Nola’s ERA (again: 4.63!) and his expected ERA (3.35) last year was 1.28 -- the largest gap in the sport.

So what gives? Well, perhaps the biggest culprits were the Phillies’ defense, which recorded a negative-20 Outs Above Average mark in ’21 (seventh worst in MLB), and the Philly bullpen, which put up a 4.60 ERA (sixth worst). Not that Nola doesn’t deserve some of the blame, but his .308 BABIP allowed was sixth highest among qualifiers, while his 66.8% left-on-base rate was the lowest. His fielders and relievers did him few favors. Even if that continues, the 28-year-old will have numbers more reflective of his true talent this season. Because nobody can be that unlucky two years in a row.

-- Jason Catania

Yu Darvish -- RHP, Padres
Key number: 22.8 K-BB%, T-8th among SP (min. 150 IP)

Darvish and the Padres both seemed to nosedive around the same time last summer, with the result being a very un-Darvish-like 8-11 record and a 4.22 ERA -- and a dejecting sub-.500 record for the Friars. But many aspects of the Darvish that dominated in 2020 were right near the surface. His ERA stood at 3.09 through his first start after the All-Star break. He still finished with 199 strikeouts, maintaining a healthy 29.8% punchout rate across his last 11 starts (even as that ERA ballooned north of six). After a forgettable final nine weeks of the season, Darvish still ranked in the top 25% of qualified pitchers in a ton of advanced metrics: hard-hit rate, strikeout rate, walk rate, expected batting average, expected wOBA and expected ERA (nearly a full run below his actual mark).

There are warning signs. If Darvish (the king of variety) has one bread-and-butter pitch, it’s the cutter that he throws about one-third of the time -- and that setup pitch got less and less effective as the summer dragged on. Darvish’s fly ball rate also skyrocketed compared to his average in recent years. It’s hard not to think Darvish’s second-half hip and back ailments contributed to his dropoff, but at age 35, those type of injuries are more likely to crop up.

Despite all of that, I just have a feeling that the Padres will sneak back up on people. The Friars’ big breakout season comes one year later than expected, and vintage Darvish will be a big reason why.

-- Matt Kelly

Zac Gallen -- RHP, D-backs
Key stat: 26.6% strikeout rate

After following up a strong rookie season with a ninth-place finish in the National League Cy Young Award voting in 2020, Gallen sustained a stress fracture in his right forearm last March and later missed time with a sprained UCL in his right elbow and a right hamstring strain.

When Gallen was able to take the mound, his effectiveness waned. His whiff and chase rates both plummeted, while his hard-hit rate spiked. Still, the righty’s 7.9% barrel rate and 32.7% sweet-spot rate were not all that different from the figures he recorded in 2020, and he was able to maintain a strong 26.6% strikeout rate. Gallen is one of 16 starting pitchers across the Majors who have recorded a strikeout rate of 26.5% or higher in each of the past three seasons, alongside top aces such as Jacob deGrom, Gerrit Cole and Max Scherzer.

It's concerning that Gallen didn't arrive at Spring Training at 100%, dealing with some bursitis in his right shoulder. But if his health cooperates, Gallen should pitch to markedly better results in 2022.

-- Thomas Harrigan

Clayton Kershaw -- LHP, Dodgers
Key number: 3.17 xERA in 2021 (best since 2017)

Now that Kershaw is back in Dodger Blue, this pick hinges entirely on health. The three-time Cy Young winner had his 2021 season derailed by discomfort in his left forearm, an injury that first surfaced in early July. Kershaw initially landed on the IL on July 4, though he returned to the mound on Sept. 13 -- and promptly turned in a pair of encouraging outings. That optimism was dashed when the discomfort flared up again on Oct. 1, forcing Kershaw from his final start of the season -- and sidelining him for the entire '21 postseason.

Kershaw had his bumps along the way last season, finishing with a 3.55 ERA, by far his highest since posting a 4.26 ERA as a rookie in '08. That said, his 3.17 expected ERA was actually his lowest since 2017, while his 29.5 K% was his highest since '17. He’s also just one season removed from posting a 2.16 ERA over 10 starts in the abbreviated 2020 campaign. There has to be some concern over Kershaw’s injury history, as he’s now had at least one IL stint in each of the last six seasons, but if he’s able to stay relatively healthy, Kershaw is always a threat for a sub-3.00 ERA

-- Paul Casella