Edward Sutelan's 2017 rankings of the top 10 Seattle Mariners MLB prospects for fantasy baseball dynasty leagues. He previews their minor league farm system.

The Seattle Mariners are coming off their best season since 2014, having finished 86-76, three games shy of a Wild Card berth and nine games shy of the AL West title. And entering the offseason, it was clear general manager Jerry Dipoto was going to improve that record by any moves necessary.

The team has definitely improved on the field and impressively, Dipoto has essentially parted with only standout prospect, pitcher Luiz Gohara. Seattle already had a depleted farm system and it certainly did not get much better, but acquiring Mitch Haniger was a solid move as was their midseason acquisition of Dan Vogelbach and draft choice of Kyle Lewis. Their prospect depth is still not great, but it actually is looking better now than it did at the start of 2016.

By the way, if you are interested in more MLB prospects columns, head on over to our 2017 fantasy baseball rankings dashboard. Throughout the offseason, you will find the rest of our team prospect breakdowns, fantasy baseball prospect rankings, tiered positional rankings, keeper values articles, and more - all in one easy place.

Seattle Mariners Top Prospects for Dynasty Leagues

Today I am continuing my list of prospect systems in the AL West. I have already covered the Houston Astros, Los Angeles Angels and Oakland Athletics farm system. Next week, I will delve into the Texas Rangers. To read more about my prospect coverage, click here.

Top Overall Talent: Tyler O’Neill

Top Prospect to Debut in 2017: Tyler O’Neill
I'm just going to put this out there: O’Neill does not have the highest upside in the system. That would be Kyle Lewis. But O’Neill is not coming off a debilitating injury. In fact, he is coming off a phenomenal season at Double-A. The slugger played in 130 games with the Double-A Jackson Generals where he bashed 24 home runs with a .293 average. He added 12 steals to his state line which, though nice, aren’t expected to be a big part of his game. This all coming a season removed from hitting .260 with 32 home runs in 106 High-A games.

O’Neill is likely to reach the big leagues this season where he should begin his big league career as a middle-of-the-order, 25-30 home run-hitting outfielder. The strikeouts are a bit of an issue, but if he can shorten his swing, he should start to make more consistent contact and reach his full potential. He could be a real solid producer at the big leagues.

Top Prospect who won’t debut in 2017: Kyle Lewis

Biggest Boom or Bust: Kyle Lewis
The 11th overall pick in the 2016 draft, Lewis has incredibly high-upside and could be a major fantasy producer for owners willing to take him on. Before his injury, Lewis was heralded by scouts as a potential 20/15 or even 30/15 threat in the big leagues with the chance to hit over .300. So what’s the risk associated with him?

I want to say that he will be safe to own, but he tore just about everything in his right knee including his ACL and it is unknown how he will bounce back from that. For some, such an injury serves as just a minor bump in the road. For others, it saps power and speed, leaving the hitter with a long recovery time. I think he will return to form and retake his spot as the most valuable asset in the Mariners’ farm system, but his injury and lack of professional exposure leave too many risks to rank him over a guy coming off a monstrous season at Double-A.

Biggest Sleeper: Mitch Haniger
My personal favorite 2017 sleeper, Haniger exploded onto the scene in 2016, bashing 30 home runs across the big leagues, Double- and Triple-A with an MiLB slash line of .321/.419/.581 and 18% strikeout and 13% walk rates. Many wonder if that season was for real seeing as how he never hit this well in any previous season, but he drastically changed his swing and found a lot of power which many scouts believe is here to stay. Now in Seattle, Haniger has a chance to start in right field for the club and he could be in line for a breakout season, really helping owners looking for some unheralded sleepers.

Top Prospect Hitters

Best Power Hitter: Tyler O’Neill

Most Likely to Hit over .300: Tyler O’Neill
Okay, okay maybe O’Neill won’t hit over .300 and maybe Lewis looks like a more reliable bet to provide that average, but like I said earlier, Lewis is too much of an uncertainty to bank on for right now. So until Lewis proves he’s healthy again, O’Neill will be most likely to hit over .300. He made great strides in improving his patience as he increased his walk rate to roughly 10% this year. Scouts have also always praised his line-drive hitting ability and believe him to be at least a decent candidate to hit for a respectable average. And as someone who has combined for 62 home runs across his past two seasons, O’Neill should not be a surprising name to see listed as the best power hitter.

Best Burner on the Bases: Drew Jackson
Jackson, like his older brother Brett, is a true burner on the base paths. The 155th overall pick in the 2015 draft, Jackson took off at Low-A, swiping a whopping 47 bags in 59 games. He ran less frequently at High-A this season, but scouts still see him as a 20-25 steal per season type of shortstop. If he can improve his swing and hit somewhere in the range of .260-.280, he could be a valuable shortstop to own.

Top Prospect Pitchers

Strikeout Machine: Dillon Overton
It may be a bit of a stretch to call Overton a “strikeout machine,” but last season at Triple-A, he struck out roughly 20% of opposing batters. The southpaw has decent stuff, stemming from his low-90s, upper-80s fastball and above-average curveball. And the decent command over his pitches gives him a bit of an advantage over opposing batters. But with that said, he’s never going to be a real swing-and-miss machine and will probably average only around seven strikeouts per nine innings.

Best Command: Andrew Moore
Moore has always been able to keep his command in check, never walking more than 6.2% of opposing hitters at any one level. When scouts evaluate Moore, the first thing that always sticks in their mind is his ability to consistently hit the strike zone and avoid walking too many batters. But while he can hit the strike zone, he lacks outstanding stuff and rarely ever gets batters to swing and miss. He’s a solid arm, but don’t expect much more than a No. 5 starter from him.

Top 10 Dynasty Prospects for the Seattle Mariners

1. Tyler O’Neill (OF, AA)
ETA: 2017
The slugging outfielder is the best Mariners’ home-grown product since Kyle Seager and could be a high impact, No. 4 or 5 hitter by the middle of this season.

2. Kyle Lewis (OF, A)
ETA: 2018
Lewis has plenty of potential to be a five-tool right-fielder, but owners will need to see how he bounces back from that knee injury.

3. Dan Vogelbach (1B, MLB)
ETA: 2017
Great plate discipline and emerging power. Vogelbach no longer flies under the radar and stands out as one of the best first base prospects in baseball. He will be the Mariners’ starting first baseman in 2017.

4. Drew Jackson (SS, A+)
ETA: 2017
Jackson is steadily developing a bit of pop, but he likely tops out as 10/20 shortstop with a .260-.270 average. Could be an underrated and valuable dynasty depth piece for owners.

5. Mitch Haniger (OF, MLB)
ETA: 2017
Haniger broke out in 2016 thanks to changes in his hitting mechanics and could be a legit 20+ power threat. He will open as Seattle’s right fielder and will have to prove he is capable of repeating.

6. D.J. Peterson (1B, AAA)
ETA: 2017
Peterson stood out as a potential 30-homer threat a couple years ago, but his raw power has not translated the way many expected it to. He still swings-and-misses far too much, limiting his upside.

7. Boog Powell (OF, AAA)
ETA: 2017
Powell is a solid, reliable hitter who expects to hit around .270 with 15-20 steals. Don’t expect much power, but his discipline and consistent contact help provide him with a high floor.

8. Ben Gamel (OF, MLB)
ETA: 2017
What was said of Powell can literally be copied and pasted right here. From their size to their skill set, Powell and Gamel are nearly twins as far as fantasy owners are concerned.

9. Andrew Moore (SP, AA)
ETA: 2017
Excellent control helps Moore appear destined for a rotation spot, but the lack of overwhelming stuff limits his strikeout potential, giving him a low ceiling and little fantasy upside.

10. Nick Neidert (SP, A)
ETA: 2019
Neidert has the stuff to get more swings-and-misses and possesses reliable control, but much like the Twins’ Kohl Stewart, his stuff has yet to equate to many strikeouts. He will need to make improvements in that area before he can be considered worth owning.

Conclusion

The Mariners’ system is top heavy with a pair of extremely talented outfield prospects, a solid first base prospect followed by a bit of a drop off. Jackson, Haniger, Peterson, Powell, Gamel all fall under the category of where they are worth owning in deeper leagues, but they do have their flaws. Haniger is the only one of that group I might say could break out and have a big season. The pitching depth is a real weakness of Seattle’s, especially after dealing away Luiz Gohara to the Braves. While no one in the top 10 is a “bad” prospect per say, O’Neill, Vogelbach and Lewis are the only must-owns in this system.