The first year in the big leagues is full of ups and downs for most players, particularly pitchers. Adjusting to the best hitters in the world simply takes time, and many hurlers need multiple seasons to find their footing.

Thus, identifying breakout candidates among second-year pitchers is no easy task, as the league has time to adjust to them just as much as they have time to adjust to the league. But doing so (or at least attempting to) is imperative for fantasy managers, especially dynasty owners trying to determine whether a player is worth keeping in the long run or targeting via trade.

Here are five second-year pitches poised for a potential breakout season in 2018.

Second-Year Starting Pitcher Breakout Candidates

Luis Castillo, Reds

A trendy sleeper pick after his eighth-place finish in rookie of the year voting last season, Castillo’s hype is well-deserved. In his first big-league season, he jumped from Double-A to the big leagues and barely blinked, posting a 3-7 record, 3.12 ERA (3.74 FIP, 3.41 xFIP, 3.63 SIERA), and 27.3% strikeout rate. Given his pitch arsenal, there’s no reason to believe he can’t sustain or improve on those numbers.

The first thing that jumps out about Castillo is his velocity. The right-hander averaged 97.5 mph on his fastball last year, third among all starters behind Noah Syndergaard and Luis Severino. On three occasions, he exceeded 100 mph — a number rarely seen from a starting pitcher. Velocity is fine and dandy, but his secondary pitches make him stand out. His changeup registered an elite 23.6% whiff rate, trailing only five other pitchers, and his still-developing slider picked up swings and misses 16.1% of the time. Castillo even developed a two-seam fastball in the middle of the season. His stuff is, predictably, difficult to barrel up, as hitters managed put up an average exit velocity of just 84.7 mph against Castillo, tied for 13th among starters with 200 or more batted balls against them.

That all sounds fantastic, but he still pitches in Great American Ball Park, right? Yes, but it doesn’t hurt him as much as other pitchers thanks to an elite groundball rate of 58.8%. Among 189 starters with 50 innings pitched, that ranked seventh. If any weaknesses pop off the page for Castillo, it’s the walk rate of 8.9%. However, his control improved as his rookie season wore on, and his minor-league track record (6.5 BB%) doesn’t suggest a reason to be concerned, either.

In terms of pure stuff, Castillo’s electric arm is unmatched on this list. If you’re a dynasty owner, this may be your last opportunity to trade for him while he’s still relatively cheap.

Dinelson Lamet, Padres

Since being signed from the Dominican Republic in 2014, Dinelson Lamet slowly moved up the Padres’ prospect rankings before making his big-league debut in 2017. The right-hander was far from perfect, but he should be on the radar of all fantasy managers heading into 2018. Called up in late May, Lamet went 7-8 with a 4.57 ERA in 114 ⅓ innings and 21 starts. His performance over his last 12 starts, in particular, turned heads. His ERA dipped to 3.38 down the stretch as he started limiting the long ball, allowing only seven home runs after coughing up 11 in his first nine starts.

But what makes Lamet a desirable fantasy arm is his ability to miss bats. As a rookie, he boasted an elite strikeout rate of 28.7%, 12th-best among all starters with 100 innings pitched. Lamet’s fastball sits in the mid-90s and touches 99 mph at times, which is complemented by a wipeout slider that generated an impressive 18.2% whiff rate. His home field, Petco Park, remains one of the most pitcher-friendly venues in baseball, which also plays heavily into his favor.

His season wasn’t without its faults, though. Lamet also had control issues, walking 11.1% of the hitters he faced — seventh-worst among starters. Of course, a pitcher can have success with a high walk rate (look no further than Robbie Ray for evidence of that), but giving up free passes makes success harder to sustain. Additionally, Lamet was essentially a two-pitch pitcher, as his changeup is not yet a reliable offering. Developing that off-speed pitch would be a huge breakthrough, helping him retire left-handed hitters with more consistency and potentially making him a top-of-the-rotation arm.

Lamet has some work to do to improve his command, but his repertoire is eye-catching and the strikeout totals alone will benefit fantasy managers. Now that he’s firmly entrenched in the San Diego rotation, it’s time to make a move for him before the price goes up.

Jose Berrios, Twins

A one-time member of baseball’s top-30 prospects, Berrios had a disastrous start to his career after a call-up in late 2016. The right-hander was optioned to Triple-A to start 2017, but he returned to the majors in May after again dominating minor-league hitters. That success continued through June, as he boasted a 7-2 record with a 2.98 ERA, 60 strikeouts, and only 17 walks in 60 ⅓ innings. After becoming a must-own pitcher in all formats, Berrios battled inconsistency the rest of the way, though he still finished with respectable numbers across the board: a 14-8 record, 3.89 ERA (4.51 xFIP), 22.6 K%, and 7.8 BB% in 145 ⅔ innings.

As Minnesota’s probable Opening Day starter after the injury to Ervin Santana, Berrios has the raw stuff to take another step forward in his second full big-league season. Berrios was largely a high-strikeout (26.3 K%), low-walk (6.9 BB%) pitcher throughout his time in the minor leagues, and his K% figures to rise as he continues adjusting to the big leagues. While he’s a fly-ball pitcher, he does a nice job of limiting hard contact. Among 99 pitchers who gave up 200 or more balls in the air, Berrios’ average exit velocity ranked 12th at 88.8 mph, which played a large role in allowing only 15 home runs all season.

The development of a sinker was a huge revelation for Berrios, as it allowed him to use his already-nasty other pitches more effectively. His four-seam fastball, which averaged nearly 94 mph and touched 98, ranked 12th in the game in terms of pitch value. And his curveball does, well, this. Unsurprisingly, batters managed a meager .248 wOBA and 63 wRC+ against the sweeping breaking ball.

If Berrios had one big fault in 2017, it was his troubles against left-handed hitters (.341 wOBA vs. .269 vs. righties). He’ll need to correct that, as well as perform better away from Target Field, but he has the arsenal to do it. At 24 years old, Berrios is already an exciting pitcher to own in dynasty formats. If he can find more consistency and reach his full potential, the Twins may have their first true ace since Johan Santana left town over a decade ago.

Luke Weaver, Cardinals

The Cardinals are known as one of the best organizations for developing pitching, and Weaver — though he didn’t get the prospect hype of Alex Reyes — is the latest young hurler ready to leave his mark in St. Louis. After a so-so showing in nine appearances in 2016, the right-hander mowed down Triple-A hitters in 2017 and got an extended look in the rotation when Mike Leake was traded to the Mariners in July.

Weaver became a fixture in the Cards’ staff and finished second among the team’s starters in fWAR in the second half (1.4). In 13 appearances (10 starts), Weaver posted a 7-2 record and a 3.88 ERA with fantastic strikeout (28.6 K%) and walk (6.8%) rates. His peripheral numbers were even better than his ERA (3.17 FIP, 2.93 xFIP, 3.29 SIERA), while his groundball rate (49.0%) was well above league average (44.0%) for starters.

The number one reason for Weaver’s solid groundball rate was his changeup. The offering complemented his 93 to 96 mph fastball very well, getting a swing and miss 13.9% of the time and forcing batters to hit it straight into the ground when they did make contact (60.7 GB%, .233 wOBA). His cutter and curveball need work, but overall, Weaver did a commendable job at limiting hard contact, resulting in an xwOBA of just .282, 24th among 187 starters with at least 200 at-bats against them.

It remains to be seen if Weaver can maintain such a high strikeout rate without a similar track record in the minors (24.2 K%), but he should be an above-average source of strikeouts at the least. The biggest question mark in 2018 will be how much he pitches. He set a career-high in innings (138) last year, but it’s unlikely he’ll be asked to go a full 200 this year. Regardless, fantasy owners should be excited to see what the former first-round draft pick can do in his first full major-league season. With a starting spot all but guaranteed after the departure of Lance Lynn, Weaver's stock is on the rise.

Lucas Giolito, White Sox

Dynasty owners have long awaited Giolito’s emergence in the major leagues, and they finally got their wish in late 2016. His first cup of coffee with the Nationals, however, did not go well, and he was shipped to the White Sox that offseason in the Adam Eaton deal. His once-high stock took a further hit in 2017 when he put up mediocre numbers in Triple-A, but he performed well in 45 ⅓ innings with the White Sox, posting a 3-3 record with a 2.38 ERA in seven starts.

There were still some red flags, however. Giolito showed much better command in the majors (6.7 BB%) than he did in the minors last season (10.7%), but that came with a below-average strikeout rate (19.0 K%), a lot of home runs allowed (1.59 HR/9), and an unsustainably high strand rate (92.0%). Giolito also experienced a dip in fastball velocity by nearly 2 mph and had trouble with his curveball — once considered a plus offering for the right-hander — allowing a .368 wOBA on the pitch and rarely throwing it due to poor command.

So what still makes him intriguing? The numbers don’t paint the prettiest of pictures, but the frame (6-foot-6) and raw stuff are still there. Even with a dip in velocity, Giolito’s five-pitch mix will make him effective if he can command it. His 12-6 curveball was once considered among the best in the minor leagues, and although he had difficulty controlling it, it would be premature to give up on the offering. Encouragingly, Giolito’s changeup made up for his curveball’s ineffectiveness, generating an elite 18.7% whiff rate.

Giolito is a safe bet to open up the 2018 season in the middle of the White Sox rotation, possibly as the Opening Day starter. If he can get his curveball back on track, it will help him break out and fulfill his high potential. At worst, he looks to be a mid-rotation arm, which gives him plenty of fantasy relevance. If another dynasty owner is willing to sell low on Giolito after a drop in his top-prospect stock, now is the time to target him.

More Fantasy Baseball Analysis