These 11 players could break out this season

March 17th, 2019

The best players in baseball in 2018 were ... well, they were and , obviously. Plus , and , and , and on and on. There's so many superstars in the game right now. But the names you know right now that you may not have a year ago included , and . A year earlier, you weren't thinking about . You can often see a breakout coming, but not always.

With that in mind, and with Spring Training in full swing, we're almost legally obligated to look ahead and offer a list of lesser-known names who are poised to make an impact on the 2019 season -- the best players you don't know yet, in other words.

This isn't about top prospects who we expect to make their mark in 2019; you should already know Vladimir Guerrero Jr. and . This isn't even about players who had huge small-sample ends to their seasons, because , and got plenty of notice, or guys who had strong full seasons that you should have noticed but didn't, like or .

No, what we're looking for players who either didn't perform well in 2018 but still offer reason to believe, or those who had a strong under-the-radar finish supported by enough data to believe it can continue. Your mileage may vary depending on whether you're a serious fantasy player or a casual fan; either way, these are names to know. (Note: Ages listed are as of Opening Day 2019.)

1) , SS, Mets, age 23
Rosario now has 762 plate appearances of mostly not being very good; his career line stands at .255/.290/.384, or an 83 wRC+ where 100 is league average. Despite that, in June, we ran a piece called "2018's Most Improved Hitters," where Rosario made the list despite a line of only .251/.284/.366 at the time. We said that because of underlying changes to his plate discipline and his hard-hit rate, but little changed production-wise for the next three months.

On Aug. 30, we checked back in, asking if Rosario's breakout was finally getting started, because he'd begun to hit, and never really stopped, putting up a line of .303/.335/.444 from Aug. 9 through the end of the year. Rosario showed huge 2017-18 improvements in strikeout rate (down from 29 percent to 20), walk rate (up from two to five) and hard-hit rate (up from 25 percent to 32 percent). He's still only 23, he was very recently a highly regarded prospect and he still has elite speed. There's more here.

2) , LHP, Twins, age 28
In a lot of ways, Rogers just had his breakout season, but we're including him here because A) he still had a 5.48 ERA through the end of May and B) there's just no way you noticed what he did after that if you weren't a Twins fan. As we went into in great detail last month, there was a strong case to make that Rogers was one of the 10 best relievers in baseball last year, thanks in part to a deadly new slider. He enters 2019 on a 28-game scoreless streak; much like his former teammate Pressly last year, he's not going to be so unknown at the end of the year.

3) , OF, Padres, age 23
The Padres have a billion outfielders, including the highly paid , former top prospect and pre-injury tools darling . The best one of them all may be Reyes, who returned from a July demotion to smash a .318/.385/.548 line with 10 homers over the final two months. Despite limited playing time -- only 285 plate appearances -- he had seven balls hit at 113 mph of exit velocity or more, a number topped by only 11 other players. The power is for real, but just as encouraging is the fact that after an untenable 39 percent strikeout rate in the first half, he cut that down to 21 percent in the second half.

4) , RHP, Phillies, age 26
Despite a 5.33 career ERA, Pivetta has become a trendy breakout pick, for two reasons. First, he just struck out 188 in 164 innings, a 27.1 percent strikeout rate higher than that of or . Second, there's considerable evidence that Pivetta was harmed by the poor Philadelphia defense more than any of his rotation mates -- and with now at short and out of left, the fielding should be better.

No, we can't believe the Phillies really got him from the division-rival Nationals for the last remnants of Jonathan Papelbon's career, either.

5) , LHP, Rays, age 23
Meet Jose Alvarado! He's a 23-year-old pitcher who just had a 2.39 ERA and 80 strikeouts in 64 innings, nice enough numbers, but not ones that truly show how good he became. Over the last two months of the season, his 47 percent strikeout rate was the second best in baseball. (Yes, he struck out nearly half of hitters after Aug. 1.) By an advanced Statcast™ quality-of-contact measure, he was one of the 10 best pitchers in the game over the last two months, as good as .

6) , RHP, Rays, age 25
Meet, also, Diego Castillo, a 25-year-old righty who touched 100 mph on 51 different occasions in 2018, the fifth-most in baseball. Serving occasionally as Tampa Bay's "opener" in his rookie season, Castillo whiffed 65 while walking only 18, and the point here is that Tampa Bay's pitching success was about more than just , (himself a breakout candidate) and weird ways to use pitchers. This roster is full of low-profile arms who blow hitters away.

7) , RHP, Rockies, age 29
Think about all the Colorado relievers you know, won't you? is the big name. Ex-Rockie was with the team last year, too. ,  and are all on sizable free-agent deals, and even gained some fame with his strong St. Louis debut. Did you think about Oberg, at all?

Here's why you should have. In 2018, he upped his strikeout rate from a decent 21 percent to a good 25 percent, and he cut his walk rate from 9 percent to 5 percent. From June 1 on, 266 pitchers threw 40 innings, and Oberg's .234 wOBA allowed was tied for sixth best. Then in the postseason, Oberg closed out the extra-inning Wild Card Game win at Wrigley Field by striking out , ,  and , before whiffing six of the 11 Brewers he saw in the NL Division Series. He'll never be the biggest name in Denver, but he might be their best reliever.

8) , SS, Royals, age 23
Mondesi's first two years in the bigs: .181/.226/.271 in 209 plate appearances. 

Mondesi in 54 second-half games last year: .286/.318/.517 with 11 homers and, wait for it, 27 stolen bases. If you're a certain kind of serious fan you likely already knew that, but it's also safe to assume that a large portion of the baseball-watching world wasn't focusing heavily on August games in Kansas City.

Mondesi should get to play daily, and he'll get to showcase that truly elite speed. The question, of course, is whether he'll hit. With a 77/11 strikeout/walk, he won't exactly be racking up the free passes, but he did put up a basically league-average hard-hit rate in 2018, meaning he's not quite the punchless hitter you'd expect from a / profile. 

9) , OF, Astros, age 22
We're cheating here, a little. Maybe a lot. But it's our list, so we get to do that. Tucker isn't exactly an unknown, because he was the fifth overall pick in 2015, and he's currently the No. 8 prospect in baseball per MLB Pipeline. The reason he's here is simple: His 2018 debut was incredibly disappointing, and we don't believe that's the real Tucker. That's partially because we're talking about only 72 plate appearances, obviously, but that .141/.236/.203 line isn't exactly impressive. 

But when you look under the hood, the hard-hit rate of 45 percent was fantastic. His expected average and slugging were .268 and .382, not .141 and .203. There may even be more of a path to playing time than you'd think, since new outfielder can play first base at times. Don't give up on Tucker just yet.

10) , OF, A's, age 24
You probably know Laureano mainly for the ridiculous throw he uncorked against the Angels last year, barely a week after he'd come up to the Majors. You know, this one.

So there's that, but Laureano is more than just one great play. He hit .288/.358/.474 in 48 games for the A's, after having hit .297/.380/.524 in Triple-A, but more important than the lines are the skills, because they're kind of loud. Laureano has 92nd percentile speed, the kind that allowed him to steal 43 bases in only 116 games in 2016; you saw the arm and defense; and a 42 percent hard-hit rate was above the Major League average of 36 percent. 

11. , IF/OF, A's, age 26
Pinder isn't Laureano, and he's not or or , but he is one of the more interesting A's we like to follow. One of our favorite stats we like to use is "Expected wOBA," which looks at the defense-free and park-free value of a hitter's quality of contact (via exit velocity and launch angle) and amount of contact. The names, of the 278 hitters who had 300 plate appearances, are what you'd expect; Betts and Trout at the top, and at the bottom.

  1. Juan Soto / / -- .366
  2. Pinder -- .365
  3. / Jose Ramirez / -- .362

Those are names, aren't they? Those are impressive names, and in Pinder's case, he made starts at every position other than catcher in 2018. He was quietly above average last year; we're thinking there's more in 2019.