I definitely have doubts on Marte, but there is a fan post from December 30th by JJ Keller over at LL that addresses the Marte future. While the article contains a few nice nuggets like:

- "Marte" somehow had the 25th BEST age 21 wRC+ since 1985, and the top 80th in the live ball ERA last year ... and he did it in just 3 months.

- The list of 21 year olds since 1985 that have had over 200 at bats and 1. BB% greater than 8%, 2. K% less than 20%, 3. OBP greater than .330, and 4. ISO greater than .100 is REALLY impressive and diverse... and there is a high percentage from this list that are MLB regulars / STARS for many many years.

- Most of these same guys from the above list had a small dip in their age 22 year

But what really caught my eye were two comments made on the article that I combined into one:

Comps for Ketel need to come from much farther back than 1985.

Tony Fernandez is decent comp, but was so much better defensively than most guys, Ketel included, it’s hard to see that as a close comp. Rennie Stennett comes to mind. He debuted at 20, and was a second baseman. Same low BB, low K, low ISO guy with speed. There were concerns with Marte’s footwork and arm strength for SS; he’s allayed those for now, but in these respects he may profile at 2B down the road like Stennett, who was just rounding into perennial All-Star form when he shattered his ankle and was never the same.

Inserted from other comment... I use Stennett because I was familiar with him, but fact is guys with the profile of Ketel Marte used to be far more common in the majors before the steroid era. Most of them were Latins, though by no means all. PEDs really changed the profile so that guys like this suddenly started hitting 20 HRs a season, and in trying to keep that up their AVG usually came down about 30 points from what they would have been, to me. Another guy who might be a comp for Ketel from back in that time would be Bill Matlock, who developed a bit more power, but was a poorer defender too. But going back into the 60s and the 50s you could find 12-20 guys like this; every team used to have one or two, although usually without any BBs to speak of and so less valuable.

The larger point is that comps based on the last 20 years are simply an inadequate base to project anything, not simply due to performance distortions but because different styles of batter offense have much deeper histories. Cross-era comparisons have problems, sure, but expanding the relationship set has the possibility to focus assessment more clearly. Not saying Stennett is a perfect comp, only that guys with Ketel’s present profile have had a history of long and productive major league careers in the live ball era. They are not flukes, it is an approach that can succeed for the guys who actually make excellent contact.

I expected Ketel to get buried in the high minors with his no BB, low ISO profile, but he turned out to be the high SD type for that profile, and really impressed me. Marte does an excellent job of making contact, has the eye and discipline to command the strike zone, and has good bat speed with a LD swing. He puts a charge into a ball when he squares if up, but isn’t swinging to put the ball in the air, and appropriately so, so his HR numbers will never be high. His ISO may well go up due to doubles and triples if he makes hard contact against more strikes. I’m hopeful on that. Marte just has better skills than the stat distribution initially suggests.

For a guy what won’t walk, the first attack is to expand the zone on him and get him to chase, and that’s exactly what was tried in AAA and the majors. Thing is, Ketel actually as a good eye for the strike zone, and the discipline to use that, and he refused to chase. Hence his BB rate spiking as he got to the top of the ladder: he wasn’t doing anything different, but the pitchers were, and that drove a change in outcomes. The other alternative is to pound the zone with quality pitches, especially for a guy who hasn’t shown much power. I expect that we’ll see this used in 2016 against Marte quite a bit. If so, his BB% will decline, again not because of him doing anything any differently. The key will be to see if his K% spikes if he’s attacked in the zone. That will decide his career.

What we saw with Taylor as he moved up the ladder was that his always good eye for the zone remained intact, but he crumbled when attacked in the zone so that his K% went way up. Marte did strike out a bit more in the majors after his 2015 promotion, but I’m not seeing that as predictive yet. He was facing the best in the game, and young for the level, and moreover he had of course never seen most of those pitchers before. If pitchers attack him more in 2016 and he can still keep his K% in single digits or close, he’s the real deal.

Marte impressed me a bunch after promotion, and he’s a high energy type too. Don’t be surprised if he’s won the crowd over by the Break if his bat holds up, and I think it will. Ketel may not break out big in 2016, but I do think he’ll beat those projections, beginning a long career. I now like Marte more than Asdrubal Cabrera coming up, and I was a big fan of Cabrera. Mookie Betts with better infield D? DeShields as more than a mirage and rather more pop? That would be quite a guy.

We all could write similar words about Chris Taylor as well, as he never really recovered from his wrist injury.

Unfortunately as it is with Martin, it remains to be seen IFFFF the reason for his decline was the wrist injury or if others factors were also were a small or significant part of their declines.  

Great stuff all around on Marte...from LL to Balthazar to Rain to Moe.  

But I'd like to move the comparison machine way back past Fernandez and Stennett to the hero shortstop of my youth...Luis Aparicio.  

On the surface, Marte (and few others) couuld ever match Little Louie in most areas:

• A defensive wizard--his top BRef comp is Ozzzie Smith.  Career 34.6 WAR in defense alone.  Off the charts on all metrics.  Nine gold gloves.
• The most feared base runner of his era. Nine straight stolen base titles.  
• The definition of 'eye'.  In more than 11 thouand plate appearances, he struck out exactly SIX more times than he walked.
• Thirteen different all star games...and an MVP award.

So how can Marte--or anyone else--be compared to him?  Well, the guy wasn't perfect:

• Despite the eye, his career OBP was only 311 (compared to league-average 329).  He neither struck out NOR walked very much.
• Career OPS+ was only 82...and exceeded 100 only once in 19 seasons.

Yes, Marte could exceed both of these last metrics.  Last year's performance was fueled by a high BABIP.  But neither contact nor hard contact indicated this was a total fluke.  

But still, how do these two guys EVER compare?

The answer lies in the highly discredited 'eye test'.  What Aparicio did was unnerve opponents.  If the current play against the M's is to keep from facing Cruz in key spots, for the White Sox of that era it was to keep Aparicio off the bases at all costs.  Because what he brought to that team (an AL team that went to the World Series instead of the Mantle/Berra/Skowron/Richardson/Kubek/Ford Yankees in 1959) was energy.  Confidence.  Spirit.  All the things that WAR can't figure out how to measure.

Could Marte be that igniter for the M's?  Well, it depends.  Depends on what Dipoto and Servais tell him--when they explain to him what kind of player they want him to be.  It's impossible to know what Al Lozez said to Aparicio.  And we'll probably never know what's said to Marte--although JD seems pretty open to this point  

But Lopez seems certain to have told Louie some version of 'just be you.  Have fun.'  Aparicio's stolen base percentage of 79% didn't set a record.  Unlikely that anyone chastised him when he got back to the dugout when he was gunned down.  And my guess is this is just the same instruction Marte had from Lloyd.  

Will the new crew try to form-fit him?  Will his inevitable sophomore slumps then be asociated (by him) with trying to be something different?

No way to tell at this point.  But when you've got a fuse that's capable of igniting a team...don't play safe and pour water on it.  

if Marin hits 9th in the lineup, this is no huge deal.  He could be the most productive #9 hitter in the AL with just a little bounce back.  

I'll go to the matt for Martin. I see 3.5-4.5 WAR in his immediate future - based on past performance.

Martin has an impressive minor league record, and a MLB record that approximates, if not surpasses Ackley's, except with stellar glove work in CF, hence the high WAR values. Like you, I chalk up last season to injury, while people a lot smarter than me are looking at their statistic models assuming there was no injury marred season, and assuming for some reason this solid player is regressing rapidly, completely apart from the injury that is staring everyone in the face.

If Ackley played CF like Martin does, we'd probably have swallowed hard and have kept him there for 2016 For the age 27 season. Good pedigrees, late bloomer template.  And we'd do this because...He's Dustin Ackley! College hitter of the decade. And he's giving us plus defense in CF. Martin? We treat him like he's dime a dozen. But look at his full body of work. 

There are many, many examples of players with Martin's pedigree blooming late and becoming solid, even star, ballplayers.