5 under-the-radar breakout hitters for 2018

Breakout hitters can come from anywhere. They can be heralded youngsters like Cody Bellinger or Aaron Judge (each were once ranked among MLB Pipeline's top 50 prospects), or they can be late bloomers like Cardinals outfielder José Martínez, who just put up some of the best contact metrics in baseball as a 28-year-old rookie.
The point is that identifying the next hot-shot hitter is an inexact science. Looking specifically at batted-ball samples from their cups of coffee last season, here's a look at five young hitters to get acquainted with before Opening Day.
Teoscar Hernández, OF, Blue Jays
It appears unlikely free agent José Bautista will be back in Toronto, and Hernandez figures to have as decent a chance as Ezequiel Carrera, Curtis Granderson and Steve Pearce to see playing time in left field. The Blue Jays acquired Hernandez from the Astros in a non-waiver Trade Deadline deal for Francisco Liriano, and Hernandez proceeded to crush eight home runs and six doubles, and compile a .908 OPS, over 26 games with Toronto. He also hit some majestic homers, including a 108.8-mph blast off Yankees ace Masahiro Tanaka last Sept. 22.
Hernandez's contact was as encouraging as his slash line. Check out where he ranked among all MLB hitters in terms of barrels -- or balls hit with the most ideal combinations of exit velocity and launch angle -- per ball in play:
Highest rate of barrels per ball in play in 2017 (minimum 50 balls in play)

1. Aaron Judge: 25.4 percent
   
2. Joey Gallo: 21.7 percent
   
3. J.D. Martinez: 19.5 percent
   
4. Giancarlo Stanton: 17.4 percent
   
5. Khris Davis: 17.2 percent
   6. Teoscar Hernandez: 17.0 percent
   One can't ignore that Hernandez also struck out 36 times and drew only six walks in his 95 plate appearances, but he could take over a corner spot for Toronto if he maintains even most of that raw power.

Drew Robinson, OF, Rangers
Robinson grew plenty familiar with the shuttle down I-35 between Arlington and Round Rock, taking three assignments to Triple-A during his rookie campaign. The 25-year-old had his struggles against right-handed pitching, batting .202, but he also showed a knack for elevating with power.
Robinson barreled up nine of the 65 balls he put in play, for a 13.9 percent rate that sandwiched him between Josh Donaldson and Nelson Cruz. The Las Vegas native knocked 11 extra-base hits in 107 at-bats while manning left field, second base and third base, and his combination of power and versatility should at least net him a utility role for Texas. There's potential for more if Robinson can improve his contact.
Lane Adams, OF, Braves
Adams wasn't far behind Robinson, barreling nine of his 74 balls in play to give him a rate commensurate with Bellinger and Michael Conforto. He also shuttled back and forth to Triple-A Gwinnett, appearing in both a Minor League and Major League game in the same day last June. Adams clubbed 10 extra-base hits in 109 at-bats, while hitting .275, and his contact was effective, producing a .421 expected weighted on-base average (xwOBA, an advanced Statcast™ metric that examines walks, strikeouts and quality of contact) that put him on par with Paul DeJong, Eric Thames and Marcell Ozuna.

Adams, like Robinson, will need to cut down on his strikeouts. But after eight strong seasons in the Minors, he appears to have the inside track on Atlanta's left-field spot for Opening Day.
Francisco Mejía, C, Indians
Mejia likely tops this list in name recognition as the Indians' No. 1 prospect and the Majors' top catching prospect, according to MLB Pipeline. Mejia has always been known as a bat-first catcher, but he's hit for a high average at every level, nonetheless. Strikeouts have also never been an issue for Mejia, unlike the other names on this list.
The most exciting part of Mejia's 2017 season was the career-high 14 home runs he hit for Double-A Akron, and that new-found power traveled with him to Cleveland last September. Mejia's pop didn't show up in his slash line (he slugged .154 in 11 big league games), but it was evident in his contact. In fact, out of nearly 700 Major Leaguers who put at least 10 balls in play last season, only two (Kirk Nieuwenhuis and the mighty Judge) averaged a higher exit velocity than Mejia at 94.4 mph.

We're talking about only 11 batted balls for Mejia, but raw exit velocity doesn't need a large sample size. It's an elite skill, and Mejia could develop into a dangerous all-around plate threat if he combines that power with his inherent bat-to-ball skills. Mejia's work at third base in the Arizona Fall League could give him another avenue onto the Indians' roster, and his bat could break into Terry Francona's lineup sooner than later.
Luke Voit, OF, Cardinals
Voit has plenty of local support as a St. Louis native, but he faces stiff competition at first base in Matt Carpenter and Martinez. If Voit can sustain the type of contact he made in 62 games last summer, however, he could be hard to keep on the bench.

Voit recorded exit velocities of 95 mph or higher -- the Statcast™ baseline for hard contact -- on 43.4 percent of his balls in play, ranking him 25th among more than 450 MLB players who compiled at least 50 batted-ball events in 2017. Ranked just above Voit on that list were marquee names like Rhys Hoskins, Christian Yelich, Bellinger and his new teammate, Ozuna.