Champ or Chump: Amed Rosario and Nomar Mazara

We are in the final stretch now, and the sad truth is that the fates of most fantasy teams have already been sealed. The players below are available in at least 30 percent of leagues, but our focus will begin to shift toward 2019 draft prep. With so much data available on so many players, you need all the time you can get if you want to have an information advantage.

Amed Rosario has elite speed, but hasn't shown any ability to translate it into stats fantasy owners care about. Nomar Mazara is one of the most polarizing players on the board, as his surface stats suggest an average performer while his backers always say that a breakout is around the corner.

Will either help fantasy rosters in 2018 and beyond?

The Fantasy Jury is Out

Amed Rosario (SS, NYM) - 32% Owned

Rosario has slashed .255/.296/.382 with seven homers and 18 steals (against 10 CS) in 2018, numbers that don't do much to excite owners. He might have a little bit of batting average upside, but he seems destined to disappoint in the SB column for the duration of his career.

Rosario hit for a strong batting average on the farm, slashing .341/.392/.481 in his first significant exposure to Double-A in 2016. Unfortunately, he managed only two homers and six steals (two CS) over 237 PAs that year. His batting average was rooted in a .433 BABIP resulting from a 26.1% LD%, marks that are almost certainly unsustainable over a larger sample size. He might be a plus BABIP guy thanks to his legs (29.5 ft./sec Statcast Sprint Speed this year) and low FB% (29.7% for Double-A Binghamton), but not .433.

The performance earned Rosario a shot with Triple-A Las Vegas in 2017, where he slashed .328/.367/.466 with seven homers and 19 steals (six CS) over 425 PAs. His LD% regressed to 21.2% (his second highest professional mark), but he still managed a .377 BABIP thanks to how easy it is to hit in Vegas (1.089 ballpark factor for hits from 2014-2016). His 27.1% FB% also supported an elevated BABIP at the expense of power upside (8% HR/FB).

The Mets gave Rosario 170 PAs in Flushing toward the end of last season, but his plate discipline was atrocious (1.8% BB%, 28.8% K%). He wasn't that bad at Double-A (8% BB%, 21.5% K%) or Triple-A (5.4% BB%, 15.8% K%), so it was probably more of an overmatched by big league pitchers thing than a chronic flaw in Rosario's game.

Rosario's 2018 looks like a success in this light, as his plate discipline stats have improved substantially (5.1% BB%, 20.2% K%). Sadly, his peripherals suggest that his plate discipline is awful. While his 39.8% chase rate is better than last season's 45.5%, it's still really bad and way too high to support his current BB%. Likewise, his 12.4% SwStr% is too high for a slap hitter even if it is a substantial improvement over his 18.1% mark in 2017. Rosario's plate discipline improvements are not something you want to bet on.

You might think that Rosario's elite wheels make his .311 BABIP sustainable, but his .243 BABIP on ground balls is only league average production. Instead, his elevated BABIP is rooted in a .127 BABIP on fly balls and a .712 mark on liners that neither his average airborne exit velocity (90.3mph) nor his rate of Brls/BBE (3.8%, roughly half of the league average) support. It's possible that he figures out how to turn his speed into base hits at some point, but nothing appears imminent.

That's problematic, as Rosario offers little else from a fantasy perspective. Somebody with his wheels should have gaudy SB numbers on the farm, but Rosario has never swiped more than 26 in a single season. His success rate of approximately 64% this year would probably earn him a red light on a contending club as well. He'll contribute something in the category, but he's no game changer.

Rosario also has no power potential at all. In addition to the mediocre contact quality metrics cited above, Rosario rarely lifts the ball (30.4% FB%) and often pops it up when he does (11% IFFB%). Citi Field is far from a home run hitter's haven, so he's not getting any help from his environment either.

Some scouting reports suggest that Rosario is a strong defender, but his defensive metrics strongly disagree (-14 Defensive Runs Saved this year). That could force him out of the lineup if the Mets get good, while making a position change more likely in the future.

Rosario has served as the Mets leadoff man in each of his games since August 5, giving him some runs potential if you need an emergency SS down the stretch. However, that's about as good as it's going to get for this version of Rosario. He's only 22, but there are too many holes in his game to count on him in 2019.

Verdict: Chump

 
Nomar Mazara (OF, TEX) - 72% Owned

It turns out that his age 23 season was not the big Mazara breakout that some projected, as he slashed .267/.328/.465 with 20 HR over 460 PAs. Most of his numbers are splitting images of his career production, so there's little growth to cling to if you want next year to be the one.

For example, Mazara has a .302 BABIP against a career mark of .297. He's somehow hitting more grounders (54.5% GB%) than he usually does (49.6% career), leaving him with relatively few batted balls for flies (26.2% FB%, 30.4% career) or liners (19.4% vs. 20.1% career). He's hitting his ground balls a little bit harder than usual (89.6mph vs. 85.6mph in 2017 and 86.3mph in 2016), helping to increase his BABIP on the ground to .266 (.242 career). He's also been aided by the willingness of other teams to deploy a shift against him (229 of 305 opportunities) despite it not working (.308 average, 52% Pull% on ground balls).

Mazara's 23.5% HR/FB is significantly higher than his 16.9% career rate, but none of his underlying metrics support the increase. His 94.6mph average airborne exit velocity is virtually unchanged from his performance in 2017 (94.9mph). His rate of Brls/BBE has increased from 6.5% last year to 8.9% this, but his decline in FB% probably negates any benefits from the spike. Mazara makes good use of his power-friendly home park (15 of 20 HR have come at home), but he just hits too many grounders for a sustained power breakout.

Mazara has hit third or fourth in each game since April 11, making him a nice addition for R+RBI if you need them. His plate discipline is also solid (7.8% BB%, 20.4% K% career). While you can always dream on a 23-year old's upside, Mazara would need to fundamentally alter his approach to reach the potential some see in him. Invest cautiously in 2019.

Verdict: Chump