Rick Lucks previews the fantasy prospects of Jarrod Dyson and JD Martinez to determine whether they will help fantasy baseball rosters in 2018.

Major League GMs are making up for lost time, as the moves have been fast and furious over the past few days. The Arizona Diamondbacks completely remodeled their outfield by signing free agent Jarrod Dyson and trading for Steven Souza Jr. Dyson is discussed below, and Souza's fantasy prospects will be considered in a future column.

The Red Sox also signed their chosen big fish in J.D. Martinez, who may already be off to a rocky start with the local media after disparaging the team during the courting process. Thankfully, PR is not a fantasy category.

Without further ado, let's take a closer look at a couple of outfielders that need to be reconsidered come draft day now that they have new homes.

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The Fantasy Jury is Out

Jarrod Dyson (OF, ARI) ADP: 418.7

Dyson had an extremely Jarrod Dyson year in 2017, as he failed to play everyday (390 PAs), put up an unimpressive triple slash line (.251/.324/.350), and still stole 28 bags (seven CS). Roster Resource doesn't currently project him as an everyday player, but Dyson has proven that he doesn't need to be to steal a fantasy-friendly number of bases. At his current price, his floor likely yields profit.

That said, there is some upside here. His 14.1% K% last season was supported by a minuscule 5.7% SwStr% and elite 91.3% Z-Contact%, ensuring that he puts a ball in play nearly every time up. Dyson also boasts an above average batting eye (27.1% chase, 7.2% BB% last year) that gives him extra opportunities to use his speed. He definitely has a clue how to handle himself in the batter's box.

Lefties confound Dyson to no end (.215/.293/.259 career), but his line is reasonable against RHP (.267/.331/.372). Last year's .251 average seems to be the result of an ill-fated effort to join the fly ball revolution. His FB% exploded (24.1% in 2016, 33.9% last year) en route to his best average airborne exit velocity and rate of Brls/BBE in the Statcast Era! Sadly, it only took 87.9 mph and a 1.7% Brls/BBE to achieve that claim.

Dyson has no power at all, so selling out for homers produced a grand total of five last year. Dyson pops up a lot for somebody with this profile (13.8% IFFB%), so the increased number of fly balls accomplished nothing but a lower BABIP (.285 vs. .308 career). Hopefully he's learned his lesson and goes back to being a spray hitter in Phoenix.

Some fantasy owners may be concerned with Dyson's age (33) and the fact that his Statcast Sprint Speed is trending downward (30 ft./sec in 2015, 29.6 in 2016, 28.8 last year). He's still very fast, and a right groin strain that kept him on the DL from August 19 through August 31 may have hindered his speed game before then. He missed nearly all of September after undergoing surgery to repair a sports hernia, so his raw speed is likely to rebound if fully healthy.

Chase Field with a humidor is a brand new ballpark, so any discussion of ballpark factors would be meaningless. Dyson is one of the few who can steal bases with Billy Hamilton and Dee Gordon on a rate basis, and David Peralta is not enough of a roadblock to worry about an ADP in excess of 400. Buy!

Verdict: Champ

J.D. Martinez (OF, BOS) ADP: 25.5

Martinez was limited to just 489 PAs in 2017, but you couldn't tell by looking at his numbers (.303/.376/.690 with 45 HR). Some regression is obviously in store as nobody is as good as Martinez looked last year, but there are reasons for optimism.

First of all, the .327 BABIP that helped produce his .303 average was actually under his career mark of .341. The principle discrepancy seems to be a sharp decline in LD% (18.5% vs. 21.2% career) that figures to rebound on its own, giving Martinez some legitimate batting average upside. His average exit velocity on ground balls (85.1 mph), reasonable Statcast Sprint Speed (26.8 ft./sec), and limited exposure to the shift (63 of 263 possible PAs, .355 vs. shift) should at least make last year's .263 BABIP on grounders sustainable. His career rate is actually higher (.281).

Martinez joined the fly ball revolution in 2017, upping his FB% from 36.2% in 2016 to 43.2% last year. This will hurt him in the BABIP department, but fantasy owners will love the sustainable power spike the additional flies offer. A 33.8% HR/FB is outrageous, but Statcast buys into Martinez's power. His 97 mph average airborne exit velocity ranked 10th in all of MLB, and two of the players in front of him (Yasmany Tomas and Matt Olson) had fewer than 150 batted balls.

Martinez's rate of Brls/BBE (19.5%) ranked third in the league. Better yet, Martinez has consistently been a Statcast monster since the data became public. In 2016, he averaged 96.1 mph on airborne batted balls with a 14.2% rate of Brls/BBE. In 2015, those numbers were 95.9 mph and 17.6%. Martinez's career HR/FB is 19.4%, and a rate in excess of 20% would be a conservative projection for 2018.

Martinez is also moving to an offense-friendly ballpark. According to FanGraphs park factors, Fenway boosted right-handed power slightly (101) while Detroit played perfectly neutral in 2017 (100). Arizona boosted power significantly (104), but the addition of the humidor means that it would not be expected to continue playing that way even if Martinez stayed. Using five-year averages for run scoring, Detroit helps offense a little (102), Boston more (104), and pre-humidor Chase Field slightly more than that (105).

If Martinez has any offensive weakness, it's his batting eye. Last season's 26.2% K% is on the high side for a .300 hitter, and his 14.6% SwStr% is ugly. His strong 10.8% BB% is more the result of his power reputation than chase rate (32.1%), which was actually slightly worse than average. Still, Martinez swings often enough (51.4% Swing%) to mitigate these factors.

Make no mistake--Martinez is an elite hitter. He's not a strong enough overall player for the Red Sox to catch up to the Yankees, but he can help you slug your way to a fantasy title.

Verdict: Champ

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