The previous 4 names were players with lots of talent, and perhaps a bit of recognition, but who might lack superstar qualities or excess helium. These next 4 have more of both (although I'm a serious doubter on #4, so his position here is based on scouting love and bonafides rather than what I see as his upside).
4) Ketel Marte - 21 yo RH SS / 2B
Upside: Jose Vizcaino / Yuniesky Betancourt / Joey Cora
Downside: AAAA tweener
Heat-meter: 8 (hit .300+ in AA as the youngest player in the Southern League, made All-Star team)
Trade value: good 2nd piece in a trade, not a headliner.
Template: Slap-hitting SS/2B with average-at-best D. To steal from what I've already said about him: Marte scares the bajeezus out of me. I don't think his swing is special, I don't think his defense is anything more than mediocre, and I don't trust his ability to hit .300, which is basically his ONLY skill. Dude walks to first with the willingness of a pirate with dual peg legs, and while he's fast (6+ triples each of the last 2 years) he's not fast enough (Taylor and Miller are both better and faster) - AND he doesn't hit doubles like he should. I like Taylor's centrifugal swing to hold up, and he can both walk more and steal at least as well as Marte.
Now, Marte was the youngest hitter in the Southern League by a full year. It was an older year for the Southern League, but even with that it's a good stat to be a young hitter and successful. He has trade value. But he can't be Jose Vidro because Vidro had 15-20 HR power even in the minors at 21. Maybe Marte will find it... but he has to find walks AND power to be Vidro. I just can't think of a guy who was a .280-to-.300 hitter at SS or 2B, never walked, and had no power and was especially IMPACTFUL. I'm up for suggestions.
Usually those guys float around the league for a good long while because they're a good stop-loss or fill-in, but rarely are they valuable in their careers as more than that. Jack Wilson had some value because of his glove. When he lost that he was basically worthless. Joey Cora was okay for a few years, but again - he took walks. Marte's profile is a hard one to see a star out of without some serious power or on-base improvement, and I'm definitely willing to part with a 90 OPS+ MIF to get something we really need. The odds of him finding either power or OBP are probably decent. Both seems like a real long-shot. Naturally this means he's going to be a 6-time All-Star as soon as he leaves the org, because Mariners Reasons.
3) Austin Wilson - 23 yo RH OF
Upside: Corey Hart / Dave Winfield-lite
Downside: John Mayberry Jr. / Mark Trumbo
Heat-meter: 5 (injury masked the fine season he had, and it was the low minors which a good prospect should conquer)
Trade value: Throw-in or 2nd piece on a lesser deal currently, like sheepskin carseat covers or a 2nd Sham-Wow
Wilson had a number of obstacles to overcome, so we knew he'd be a bit of a project. First was his Stanford Swing, which robbed him of all his natural (and BP) power. He's done a good job at that (top-5 bat in the MWL, and trust me, it's hard to OPS .900 there). He's gotten much shorter to the ball and can rip it now. Second is staying healthy, and he wasn't good at that this year (or his last year of college). Still, they were different injuries and neither the arm nor the ribs should be lingering issues. Much like I didn't care about Rendon's injuries, I don't care about Wilson's. He has all the tools - a huge guy with 20-steals speed, massive power in BP that is starting to translate to games, a good arm to the plate... he doesn't walk as much as you'd think, but neither does his ultimate comp Giancarlo Stanton, who is built much the same way and has a similar game. Can Wilson get there? Almost no one can.
Can he get to be a good enough Stanton-lite (or Winfield-lite for the previous generation of baseball watchers) to be extremely valuable to us? Absolutely. Austin Wilson is still under the radar this year due to his low-minors stay and losing half the year to that injury. But if there's one guy whose stock could shoot through the roof next year it's Wilson. I hold on to him if at all possible. I just don't think Mayberry is his future - I see him more as a Corey Hart type, and prior to the last couple years that was a very good thing.
2) Patrick Kivlehan - 25 yo RH 1B/3B/OF
Upside: Brian Jordan / Alex Gordon
Downside: Josh Fields, the hitter (Who? Exactly. KC prospect from a few years ago)
Heat-meter: 7 (Hit .300 in Southern League, 5th in OPS, "old for level" and sliding down to lower defensive positional value)
Trade value: good 2nd piece in a big trade or lead dog in a moderate one, not a headliner.
Patrick gets excuses made for him like, "He's raw. He's untutored. He's just getting the hang of this." Which are all true... but yet Kivlehan's career line is .300/ .365/ .490. And it's about the same whether he's in short-season or AA. He is growing with his competition. His eye is over .5 now which is pretty amazing considering where he started (38 Ks before his 2nd professional walk). His power remains fine outside of the Desert. He won't play 3B long-term but the guy can fly around the field just fine for a thicker man. He could play 1B, but I'd put him in the OF. Alex Gordon had been bouncing back and forth to the majors by age 25, but he had quite a head-start on Kivlehan too from a college-ball perspective. Kivlehan will be looking to turn it on in his mid-20s like Jayson Werth or Matt Carpenter did. Can he?
I sure wouldn't trade him for anything short of a superstar-for-package sort of deal, because I want to find out. Adding an Alex-Gordon-type to the OF with a lot of range, a gun and some pop would be great. Kivlehan hasn't met a baseball challenge he hasn't conquered yet. Let him keep trying. Due to age-prejudice he's not bringing you back anything huge by himself anyway, so enjoy finding out whether he can be some version of Gordon/ Ryan Zimmerman at the plate for us.
1) DJ Peterson - 23 yo RH 3B/1B
Upside: Hunter Pence / Mike Cuddyer
Downside: Rich Poythress
Heat-meter: 7 (Futures Game participant and AFL All-Star with a .914 career OPS, bad luck w/ injuries and defensive concerns)
Trade value: Headliner as a recent 1st round pick with helium left
Out of college, the question was whether DJ could actually hit (for power especially), or whether he was simply a product of a launching pad in Albuquerque. A year and a half later, there are still people on either side of that fence. His career line is .300/ .365/ .550-ish, and the guy hit 30 doubles and 30 homers last year. Of course Rich Poythress did once too, and his career never went anywhere. I think DJ is a better pure hitter than Poythress was and much like several of our other prospects, pure power is not the reason I'm high on Peterson. He should hit hit for a pretty high average and can drive in plenty of runs, although he may never be a superstar. It's no shame to be a really good 2nd or 3rd banana on a team - ask Seager (or Cuddyer or Pence).
When he was drafted I said offensively DJ reminded me of Billy Butler, but he has more positional versatility than Billy, so I'm listing Pence and Cuddyer as guys who were similar at 21-23 years old in the minors and have had the sorts of careers I could see for Peterson if he pans out. DJ will likely not last at 3rd base, much like Kivlehan, and a move to 1B or the OF hurts him theoretically - but I didn't think he'd be a 3rd baseman when we drafted him. IMO, we were always drafting him to play 1B or an OF corner. Love his swing shape, and if he can get away from these weird injuries that are slowing him down a touch I don't see any reason he won't be up and contributing for the 2016 Mariners... assuming he's still here. He has the most trade value of any hitter in our system, and if we're aiming for a superstar instead of another banana, DJ may have to go to get him for us.
I left off:
Julio Morban - too-oft-injured to have trade value, but such raw potential in a Carlos Gonzalez way if he could stay healthy... been in the system since 2009 and still just 23 to start the 2015 season, but his career high in seasonal PAs is 352. Terrible 2014 though.
John Hicks - decent 2014, just turned 25, good defensive catcher with some potentially-decent plate skills, though barely any power. Not a lot of people give up much for a defensive backstop these days, but he might be a piece that goes if we don't want "I love getting HBP" Zunino being backed up by a rook. I would think we'd rather give him up than Marlette. My guess is we keep him and season him a bit more. Catchers tend to find their stride around 26, 27. Hicks is rising nicely in the oven.
Dario Pizzano - Abysmal BABIP this past season killed his batting average and obscured the fact that his core skills (great batting eye, 100+ points of patience, .180 ISO) remained intact. It almost certainly killed his trade value, however. Turns 24 in April and is in the upper minors, so he's not lagging. If the hits fall at his normal rates next season, he could compete as a dark horse for an OF spot for sure.
Dan Paolini - I called him a Dan Uggla type a couple years ago, but he's been moved off 2nd. The former pitcher is still hitting (.810 OPS in AA this last year) and he's never struck out more than 80 times in a season so his contact skills are pretty good. Still, talking teams into playing Uggla at 1B would a tough sell, and it won't make Paolini's route to the bigs any easier either.
Jabari Henry - Jabari had a good year, but has several problems. Other outfielders are more highly rated, and High Desert is hard to make lasting impressions off of. I'm so glad to be out of that place. The prospect mention under Gabe Guerrero's writeup, Johermyn Chavez, posted a .315/.390 /.575 line in the Desert (AFTER an .820 OPS previous season in the MWL at 20) and crashed back to earth to the tune of .215/ .310/ .360 in AA. Other teams are loathe to put too much weight to those High Desert performances. If he pulls a Kivlehan this coming year, his stock can rise quite a bit. Definitely keeping a close eye on him.
Jabari Blash - that suspension hurts his value quite a bit, so I think he'll have to recover his prospect-hood this upcoming season in AAA. The shadow of our Liddis and Pegueros still looms large; we're good at guys with terrible zone judgment and lots of power... who never get better. He'll have to show he can shore up his weaknesses, so the good news is he'll be around to do that for us.
If you think I missed somebody you wanted to hear about (cue the Tyler Smith lovers), or want to talk about anybody on or off this list please do so. As I look at our hitters I don't see a lot of headliners we could trade for a MOTO superstar. Luckily we have a lot of positional duplication. We could trade DJ, Wilson and Marlette and still have Kivlehan, O'Neill and Hicks at those positions, plus more. On the big league club we can swap out either Miller or Taylor, or one of Saunders or Ackley if we add an outfielder. We can be flexible, which is a good thing when orchestrating trades to get the most potential partners.
We aren't creating a hole by trading the top players we do have at those positions - assuming the other guys can produce. The Rangers dumped both Smoak and Davis when they had a 1B positional surplus, but Moreland didn't exactly crush it for em, and they wound up with another trade at 1B. Hopefully the guys we keep can actually step up and turn into their best selves. Other than Seager, nobody's been doing that. Let's try for a nice change, yeah?
Coming at some future time: pitchers! Last spoiler alert of the day: there's not a headline option there either (not already on the big club) but there are some nice arms that could fill out any trade. Maybe even a co-headliner in the right package.