With fantasy prospect rankings, the key to knowing the usefulness of a specific player is how large and deep of a league you would need to be in for them to end up as a fantasy starter. We will be ranking 10 prospects in each system, but that doesn't mean that every one of them is useful if you play in a 12-team mixed dynasty league. With that said, we're aiming to provide useful information whether you play in a 10-team mixed, a 15-team AL-only, or a 24-team mixed.
Prospect rankings also come with the same caveat that must be rehashed every year. They represent a snapshot of how we view the players at the time of publication. There will inherently be more information published throughout the off-season, and so how we view a player may evolve significantly over time. We're going to get some of these right, we're going to get some of these wrong, and in general my reminder is to find information you trust, and use it to your advantage. If that comes from us, that's great and we're happy you're here. If it doesn't, we'll continue to work and hope that you'll keep checking in to see how we're doing.
The tiers are here though to provide some clarity when comparing players between different teams. It's by no means a perfect system, but the goal is to give you a general idea of which players we think are in a similar range in terms of value and ranking. Since the tiers are also expected to be relatively consistent across teams, there may be tiers that do not have prospects for certain teams.
Tier 1 - The Elite Prospects
These prospects are expected to be in the top-50 prospects overall, and have the potential to be among the top options at their position regardless of format or league size.
#1 - Kyle Lewis (OF)
Age on Opening Day 2017: 21
Lewis was a consensus top-ten talent in the 2016 draft class, on the strength of his bat speed and high-end power, and was named Baseball America’s College Player of the Year just two days before being selected 11th overall. He dominated the Northwest League for thirty games, slashing .299/.385/.530 with 16 extra-base hits, 3 SB, and nearly as many walks (16) as strikeouts (22), and seemed poised for a promotion. Unfortunately, a torn ACL ended his season on July 19, and may have him sidelined until June of this coming season. Nevertheless, Lewis has the above-average hit tool and plus-plus raw power to project as a true middle of the order bat - his timetable will just be a bit delayed.
#2 - Tyler O’Neill (OF)
Age on Opening Day 2017: 21
O’Neill burst into the prospect scene in 2015, smashing 32 HR and swiping 16 bases at High-A Bakersfield, turning 20 halfway through the season. There were plenty of skeptics, however, due to the hitter-friendly environs and some disconcerting plate discipline markers (notably, a 6.5 BB% and 30.5 K%). O’Neill’s follow-up could not have gone much better, as the now 21-year-old slashed .293/.374/.508 with 24 HR and 12 SB (2 CS) with much improved walk (10.8%) and strikeout (26.1%) rates in the context-neutral Southern League. His base-running prowess is based more on good instincts than raw speed, so the stolen base totals may slip over time - but his improved approach, solid average hit tool, and plus to plus-plus raw power make him a top flight outfield prospect.
Tier 2 - The Top 100 Candidates
These prospects are expected to be in the discussion for the top 100 prospects overall, and are expected to be starting options in all formats.
Seattle has no prospects in this tier.
Tier 3 - The Next Group of Starters
These prospects would likely slot into the 100-200 range on an overall ranking list, and would be starters in mid-depth formats, like 12 and 14 team leagues.
#3 - Luiz Gohara (LHP)
Age on Opening Day 2017: 20
It would be an understatement to say that the Mariners have brought Gohara along slowly, as the 20-year-old just set a career-high with 81.1 IP (69.2 between Low-A and Single-A, and 11.2 in the Arizona Fall League). He has thrown just 216 IP over four seasons as a professional, and has largely been more promise than production. That began to change this season, though, as Gohara consistently showed two plus pitches (a mid-90s fastball and wipeout slider), and trimmed his walk rate by more than five percentage points. He can dial the fastball up to triple digits, as well. His change-up remains a work in progress, and he is still building up stamina - but Gohara has a top of the rotation ceiling. The fact that he was able to slim down considerably speaks to his work ethic, too.
#4 - Nick Neidert (RHP)
Age on Opening Day 2017: 20
Neidert lacks ideal size for a starting pitcher, checking in at 6’1” and 180 pounds, but that may well be the only genuine flaw in his profile. The 2015 second round pick flashes a plus fastball, plus curveball, and average slider, and has long garnered praise for his control and pitchability. His fastball sits in the low-90s (though he can reach the mid-90s at times), and he has the ability to put it most anywhere. While Neidert may not have the strikeout totals to be a high-end fantasy starter, he profiles as a capable mid-rotation starter that will limit walks and keep the ball in the park.
Tier 4 - Single League and Deep Format Plays
These prospects would likely slot into the 200-300 range on a ranking list, and would have the most value to mixed leagues with 16+ teams and single-league formats with 12+ teams.
#5 - Alex Jackson (OF)
Age on Opening Day 2017: 21
A bit over two years ago, Jackson was Baseball America’s High School Player of the Year, and one of the most highly regarded prospects in the 2014 draft class. He was ranked 20th by BA heading into the 2015, and 28th by MLB.com. And then 2015 happened, and we were forced to take a step back. He hit a respectable .243/.332/.408 at Single-A this season (20% above league-average by wRC+), with 11 HR in 381 PA. Jackson dealt with lingering injuries throughout the season, but the plus bat speed and plus raw power were on display - and he won’t be 21 until Christmas Day. He is a divisive property, though, with James Fisher of Baseball Prospectus projecting him “as a power bat off the bench,” due to major questions about his hit tool. (The Mariners traded Jackson to the Braves about eight hours after this was finished - he won’t make their top-ten, so I felt it best to leave here for posterity)
#6 - Dan Vogelbach (1B/DH)
Age on Opening Day 2017: 24
Were it not for my desire for proper formatting, I would have listed Vogelbach’s position as “1B, allegedly,” as the soon to be 24-year-old doesn’t really have a position outside of the batter’s box. Luckily, the Mariners play in the American League, where he can play almost every day as the designated hitter - a role that he was born to fill. He has an above-average hit tool, above-average bat speed, and, to some, elite raw power, as evidenced by his .292/.417/.505 slash line with 23 HR in 563 PA at Triple-A in 2016. Vogelbach does struggle against LHP (though his .791 OPS against them last year was solid), so he may sit against tougher ones - but he could fit snugly into the utility spot on most fantasy rosters with a solid batting average and 25-plus home runs.
#7 - Mitch Haniger (OF)
Age on Opening Day 2017: 26
The recently acquired Haniger is old for a prospect, but there are reasons to overlook that (to an extent). He completely reworked his swing in the off-season between 2015 and 2016, and dominated at both Double-A (.294/.407/.462 with 4 HR and 4 SB in 236 PA) and Triple-A (.341/.428/.670 with 20 HR and 8 SB in 312), prior to earning a call to the Show (where he hit another 5 HR in 123 PA). Haniger has long been regarded as a player with above-average to plus marks in his power and speed and, while he was never bad in the minors, he had never been as productive as he was in 2016. He may end up in the short side of a platoon, but there’s a real chance that he can chip in 15-plus home runs and 12-plus steals with enough playing time.
#8 - Ben Gamel (OF)
Age on Opening Day 2017: 24
Gamel repeated Triple-A in 2016, and saw his power dip quite a bit, with his ISO slipping from .172 to .112. The 24-year-old boasts a solid average hit tool and above-average speed, and it’s easy to see him batting .270-plus with 20 or more steals in a full season. His power, however, is what will determine his ultimate value. Gamel hit 10 HR in 2015 and 6 last season, and some feel that he could hit upwards of a dozen at the highest level. If he can hit double-digit home runs (and get the playing time that that would require), he could be a decent fourth outfielder on most fantasy teams.
Tier 5 - We Ranked Ten Prospects, We Really Did
These prospects generally will be useful in the deepest of formats. Think 24+ teams for mixed leagues and single-league formats with more teams than the league it uses. In many cases, these will be part-time players or utility-types when they get to the majors.
#9 - Ryan Yarbrough (LHP)
Age on Opening Day 2017: 25
Last year, I described Yarbrough as unexciting, due to his profile as a soft-tossing left-handed pitcher. And ... not much has changed. His strikeout rate slipped against more advanced bats, dropping from 8.19 K/9 at High-A to 6.94 at Double-A, and that trend is likely to continue. He tossed a career-high 128.1 IP in 2016, and has the build that suggests that he can throw 180-plus regularly. If he can do that while keeping the walks down and the ball in the park, he could be a solid back of the rotation starter.
#10 - Joe Rizzo (3B)
Age on Opening Day 2017: 19
Our last two spots on this list were largely wild cards, albeit for different reasons, and Rizzo is ambitious (to say the least). The 18-year-old was drafted 50th overall in 2016, drawing praise for having one of the best hit tools among high school prospects in the class. John Manuel of Baseball America rated him as the best pure hitter among Mariners picks, ahead of the number one prospect on this list. Rizzo hit .291/.355/.392 in the Rookie Level Arizona League, and convinced some folk that he can stick at third base. His hit tool has true plus-plus potential, and his swing and raw power portend solid average in-game power. He’s several years away, and has a great deal of risk - but he could hit .290-plus with 15 home runs at the hot corner.
#11 - D.J. Peterson (1B) or Drew Jackson (SS)
The aforementioned Alex Jackson trade brings us here. Peterson was the last player on my list (and first one out), and the other Jackson filled the same spot for Michael.
Peterson is a 1B-only prospect, with plus power and a fringe-average hit tool. He produced a solid .264/.327/.455 slash line between Double-A and Triple-A in 2016, with 19 HR in 504 PA, quelling some of the doubts about his ability to actualize his hitting ability that arose in 2015. It’s not an eye-popping profile by any means - but he could get a shot at the Majors this year, and could be a middle of the pack run first baseman in time.
And Jackson is an athletic marvel, with plus-plus marks in his arm and speed. That speed wasn’t on display much this season, however, as he stole just 16 bases (and was caught eight times), and picked up only two triples. His overall slash line of .258/.332/.345 in 596 PA in mostly hitter-friendly parks leaves a bit to be desired, as well. At this point, Jackson is firmly in the promise over production pool, and may well be a better real world than fantasy player.