1) RHP Rookie Davis, Reds
Three of the four pitchers who made this list have never appeared in a game above the Double-A level. Of those three, Davis has thrown by far the fewest Double-A innings, so he could be viewed as an extreme longshot to reach the Majors in 2016, let alone contribute. On the other hand, Davis already has accumulated more Double-A innings than Lance McCullers had last season when the Astros promoted him to the big club. Davis is four months older, four inches taller, and forty pounds heavier than McCullers. According to Baseball America, Davis ranks as Cincinnati's #9 prospect, whereas McCullers entered last season at #11 in Houston's farm system. None of this guarantees that Davis will make it to Great American Ballpark in 2016, but one cannot dismiss the possibility, particularly in light of the rebuilding Reds' young and injury-riddled rotation.
When Davis does arrive in Cincinnati, he will bring a starter's repertoire and a record of recent minor-league success that fantasy owners should not overlook. His three-pitch mix of fastball-curveball-changeup includes both swing-and-miss stuff--he whiffed 105 batters in 97.1 IP at High-A Tampa--and excellent command, as shown by his career 2.35 BB/9 ratio in the minors. So if you'd like to be the owner in your league who picks up a much bigger and more successful version of Lance McCullers, keep an eye on Davis.
2) LHP Josh Hader, Brewers
When you follow hundreds of prospects each season, you're bound to fall in love with a handful of them. Hader has been "that guy" for me since his days in the Orioles system, before he was traded to Houston and then to the Brewers. In December I wrote about him for Baseball Prospectus Milwaukee. I pounded the table for Hader because he seemed chronically and criminally underrated. Finally, unprompted by my table-pounding, John Sickels ranked Hader #5 in a loaded Brewers system, declaring that he "must be the high guy" on Hader. Indeed. And welcome to the club!
Hader, 21, has posted impressive minor-league numbers despite always being young for his level. A 19th-round pick in 2012 from Millersville, MD, Hader has befuddled hitters to the tune of 398 strikeouts and a 2.95 ERA in 363.1 career innings. In 2014 he was named Pitcher of the Year in the hitter-friendly California League, where ERAs soar and pitcher egos deflate. Last season he managed a 3.03 ERA between Double-A Corpus Christi and Double-A Biloxi, striking out 119 in 104 IP. Then, he capped a remarkable two-year run of success with a dominant performance in the Arizona Fall League (16 IP, 0.56 ERA, 7 BB, 19 K). Milwaukee's starting rotation appears set, so if Hader gets an opportunity in 2016 it will be because he forces the issue at Triple-A Colorado Springs. Given his track record, I would not bet against it.
3) RHP Jorge Lopez, Brewers
Speaking of young Milwaukee starters banging on the rotation door, Lopez in 2015 burst onto the prospect scene with an outstanding season at Biloxi (2.26 ERA, 52 BB, and 137 K in 143.1 IP). A former second-round pick, Lopez features a solid fastball-changeup combo and a putaway curveball that he commands like a frontline starter, which is his ceiling. A pair of late-season starts in the big leagues did not go as planned--14 hits and 5 walks in 10 innings--but Lopez remains the consensus #1 pitcher in the Brewers system.
As is the case with teammate Josh Hader, circumstances beyond Lopez's control will dictate the extent of his opportunity to contribute in the Majors this season. Although the Milwaukee rotation appears set, neither Chase Anderson nor Matt Garza could afford a prolonged period of struggles before the fan base begins clamoring for prospects such as Lopez and Zach Davies. And once Lopez arrives in Milwaukee, he might be there to stay.
4) LHP Steven Brault, Pirates
Unlike the Reds and Brewers, the Pirates plan to contend in 2016. Gerrit Cole and Francisco Liriano lock down the top of the rotation, while aces-in-waiting Tyler Glasnow and Jameson Taillon should arrive in Pittsburgh this summer. The Bucs have at least three additional LHPs--Jon Niese, Jeff Locke, and Kyle Lobstein--ahead of Brault on the depth chart.
So why should fantasy owners pay Brault any attention? For one, Brault opened eyes with his performance last season in 28 overall starts and especially in the 15 he made with Double-A Altoona, where he finished with a 2.00 ERA, 19 walks, and 80 strikeouts in 90 innings. He has three average pitches that play up thanks to his outstanding command. Like the other pitchers on this list, Brault could force the issue if he excels at Triple-A Indianapolis, for the back of the rotation is one place that an unheralded prospect could make an impact for this otherwise strong Pittsburgh club.
5) OF Charlie Tilson, Cardinals
Tilson, 23, spent all of 2015 with the Double-A Springfield, where he slashed .295/.351/.388 and led the Texas League with 46 steals, by far a career high. With only 15 HR in nearly 1500 minor-league ABs, Tilson has not yet developed the power one would expect from a corner outfielder, which is why he profiles as a centerfielder and top-of-the-order table-setter.
Tilson's chances of making an impact at the Major-League level in 2016 seemed negligible until news broke that veteran LF Matt Holliday was taking ground balls at first base, where he could serve as the right-handed half of a platoon with either Matt Adams or Brandon Moss. That arrangement alone would not open the door for Tilson, but it does show that the Cardinals are willing to get creative, for they have to know that an outfield of Holliday, Randal Grichuk, and Stephen Piscotty would not be their best defensive alignment. Tilson could prove that he's the organization's best internal option in CF if he gets off to a fast start at Triple-A Memphis. If that happens, and if he gets the call to St. Louis for regular playing time, his stolen-base potential alone would make him relevant in all roto leagues.