Yesterday, MLB.com looked at position players who impressed in their debut seasons in 2018. Now it's time to turn attention to those who stepped on a big league mound for the first time this year.
While there were numerous pitchers who tasted success in their initial MLB opportunities, here are 10 who stand out not only for their results, but also the way in which they produced those results. With an assist from Statcast™, each is paired with a stat that helps show why his performance is so intriguing. (Pitchers are listed in descending order of innings pitched in 2018).
Ryan Yarbrough, LHP, Rays
Key stat: 26.9 percent hard-hit rate
Yarbrough's line might cause a double take -- he went 16-6 despite starting only six games. That was the product of Tampa Bay's use of "openers" on the mound, with Yarbrough typically coming in afterward and going multiple innings. Unorthodox usage aside, the 26-year-old was able to post a 3.91 ERA, in large part because of how he limited hard contact (95-plus mph exit velocity). Of the 139 pitchers who allowed at least 300 batted balls, five had a lower hard-hit rate, including two (Carsten Sabathia and Chris Sale) in the AL.

Dereck Rodriguez, RHP, Giants
Key stat: 3.9 percent barrel rate
He's not just Pudge's kid anymore. Rodriguez was the Giants' best starter in 2018, outpitching Madison Bumgarner in a similar number of innings (118 1/3). The 26-year-old didn't generate tons of strikeouts or ground balls but nonetheless made it difficult for opponents to square him up for barrels -- the most dangerous form of contact, according to Statcast™, based on exit velocity and launch angle. Rodriguez's barrel rate tied Carlos Martinez for third lowest in MLB (minimum 300 batted balls), behind only Noah Syndergaard and Mike Montgomery, and just ahead of NL Cy Young Award winner Jacob deGrom.

Shane Bieber, RHP, Indians
Key stat: 20.5 percent called-strike rate
Bieber's 4.55 ERA across 20 games (19 starts) doesn't look like anything special, but among MLB pitchers with at least 100 innings, the 23-year-old ranked 18th in FIP (3.23), tied for 11th in walk rate (4.7 percent), and tied for 10th in strikeout-to-walk ratio (5.1). A big key was Bieber's ability to pound the strike zone. Of the 135 starters who threw at least 1,500 total pitches, Bieber had the 10th-highest rate of in-zone pitches (53.5 percent), sandwiched between Max Scherzer and Gerrit Cole. Only Kyle Hendricks and Rich Hill drew a higher percentage of called strikes, and Bieber was 14th in overall strike rate (67.4 percent).

Freddy Peralta, RHP, Brewers
Key stat: 77.7 percent four-seam fastball usage
It's difficult to believe a righty could succeed while throwing a four-seamer -- one that averaged under 91 mph -- more than three-quarters of the time. And yet, here we are with Peralta. The 22-year-old posted a 4.25 ERA, 3.72 FIP and excellent 29.9 percent strikeout rate over 16 games (14 starts), then notched six Ks over three hitless innings in Game 4 of the National League Championship Series. While his curveball was an effective second pitch, Peralta threw his high-spin, "invisible" four-seamer far more often than any other regular MLB starter, and opponents batted just .195 against it.

Jordan Hicks, RHP, Cardinals
Key stat: 100.5 mph average fastball velocity
For the first time since 2012, Albertin Chapman did not lead the Majors in this category. Instead, he was dethroned as MLB's No. 1 flamethrower by a 22-year-old who had not pitched above Class A prior to this year. Not only did Hicks finish 1.6 mph ahead of Chapman, but he did it while throwing sinkers -- some of which seemed to defy the laws of physics with late movement that was perhaps even more impressive than the velocity. Hicks threw a whopping 659 pitches that reached triple digits, more than three times as many as anyone else. He also was responsible for 39 of the 50 fastest individual pitches, including two that popped at 105 mph.

Adam Cimber, RHP, Padres/Indians
Key stat: 2.07-foot average vertical release point
It's fun when someone does things a different way, and Cimber certainly qualifies. Though he was less effective after a trade to Cleveland, the 27-year-old rookie still finished 2018 with a 3.42 ERA in 70 appearances despite throwing mostly 86-87 mph fastballs. Cimber succeeded by getting lots of grounders and posting one of MLB's lowest barrel rates, with his unusual delivery likely playing a big role in throwing off hitters' timing. Cimber may have the most extreme release point in the game. It was lower than anyone's other than fellow Padres rookie Kazuhisa Makita (a 33-year-old from Japan), and tied for the 12th widest by either a righty or lefty (3.54 feet).

Seranthony Dominguez, RHP, Phillies
Key stat: .185 expected BA allowed
Aside from one short rough patch in August, Dominguez was pretty dominant out of the Philly bullpen after debuting in May. Pairing a 98-mph fastball with an 89 mph slider that generated a whiff rate above 50 percent, Dominguez ranked in the top 25 in MLB (minimum 50 innings) in both strikeout rate and ground-ball rate. That helped him tie Scherzer for the 16th-lowest xBA -- which factors in strikeouts and quality of contact -- among more than 350 pitchers who faced at least 200 batters.

Justin Anderson, RHP, Angels
Key stat: 37.2 percent whiff rate
Here are the only pitchers who missed bats on a higher percentage of swings than Anderson in 2018: Hector Neris, Jose Leclerc, Craig Kimbrel, Edwin Diaz, Josh Hader, Dellin Betances and Chapman. It certainly helps when you throw a slider more than half the time -- and get one of MLB's highest whiff rates with that pitch (52.6 percent). The side effect was an unsightly walk rate (16.6 percent), but Anderson also racked up lots of Ks, and opponents batted just .214 with a .276 slugging percentage against him over 57 appearances.

Shohei Ohtani, RHP, Angels
Key stat: .036 BA allowed on splitters
Ohtani already was discussed on the list of impressive first-year hitters, and although he threw just 51 2/3 innings in 2018 -- and likely won't throw any in '19 -- he certainly deserves mention here as well. Ohtani's fall-off-the-table spitter was perhaps the most devastating pitch in the Majors this year. Opponents were basically helpless against it while also having to guard against his mid- to high-90s fastball and nasty slider. The splitter induced a miss on 55.8 percent of swings, and batters went a laughable 2-for-55 against it, with one double, no homers, a .055 slugging percentage, and 35 strikeouts.

Framber Valdez, LHP, Astros
Key stat: 2929 RPM average curveball spin rate
A Houston hurler with a high-spin curve is nothing new. Of the 170 pitchers who threw at least 150 curves last season, Valdez's spin rate was seventh highest; Thomas Pressly, Charlie Morton, Justin Verlander and Cole also ranked in the top 20. Opponents went just 4-for-41 (.098) with 20 strikeouts off Valdez's hook, putting 17 of their 21 batted balls on the ground. Walks were an issue during the 24-year-old's brief time in the Majors (37 innings), but he posted a top-five ground-ball rate overall (70.7 percent) and could challenge for a rotation spot next season, along with fireballing fellow rookie Josh James.