Each week in this report, I’ll be monitoring the performances of MLB rookies. I will emphasize those rookies who put up especially positive performances, while also taking care to mention rookies who are underperforming expectations. In both cases, I will dig into the underlying stats and attempt the difficult task of projecting forward. Rookies are typically more unpredictable than their more experienced colleagues, and can, therefore, be a source of great profit in fantasy baseball; or great frustration. Stay tuned to this space every week to find out which newbies should be in the mix for your squad.

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Rookie Risers

Mitch Haniger (OF – SEA)

The 26-year-old Haniger snuck in under the 130 at-bat threshold to retain rookie eligibility entering 2017. After destroying minor league pitching in 2016, Haniger displayed some patience and power at the major league level, but a low BABIP held down his batting average. Moving from Arizona to Seattle with Jean Segura, Haniger was handed a starting role in the Mariners outfield, and has started hot with three HRs and one SB. Thanks to a strikeout rate near 30%, his AVG stands at only .242, but he continues to show a strong walk rate. Batting average will not likely be a strength for Haniger until he can curb his Ks, but 15 HR and 10 SB seem easily within reach. If he is available in your league, he makes a nice bench OF or 5th OF streamer for daily leagues.

Manuel Margot and Hunter Renfroe (OF – SD)

This pair of Padres displays a tantalizing mix of power and speed. Renfroe hit 34 HRs between the minors and majors last year, including four in a blistering 11-game audition with the big club. Margot found more modest success in 10 games, but the former Red Sox prospect did steal two bases without being caught. In the early going this season, Margot, surprisingly, has three HR, while Renfroe has two. Margot has posted a .323 AVG batting leadoff for the Padres, while Renfroe has managed a .281 AVG hitting fourth or sixth. Neither has a history of high walk rates or high strikeout rates and AVG is very unreliable this early in the season, so the best bet is to expect around a .260 AVG for each going forward. Renfroe will likely chip in 20 more HRs and a few steals, while Margot should be expected to steal over 20 bases. Originally projected for a single-digit HR total, if Margot can eclipse 15 long balls hitting atop the lineup, he will be a 2017 breakout star. The early power returns suggest this is possible, despite having hit two of his three homers off Matt Cain.

Aaron Judge (OF – NYY)

I confess that I was ready to dismiss Aaron Judge after he posted a 44.2% strikeout rate in almost 100 plate appearances last year. For someone with 70-grade raw power, he had never hit more than 25 HR in a single year coming through the Yankees’ system. However, of any player with more than 20 batted balls in 2016, Judge had the highest average exit velocity on line drives and fly balls, at 100.2 mph. This suggests that Judge may have been unlucky to post only a .167 isolated slugging percentage (ISO) in 2016. So far in 2017, Judge has hit .261 with a .304 ISO and two HR. More importantly at this early stage, he has struck out in a manageable 24% of his plate appearances. His 13.8% swinging strike rate (SwStk%) is well below his 18.1% mark from last year, and would place him among established high power, high strikeout sluggers such as Mark Trumbo, Chris Davis, and J.D. Martinez. Despite the solid start, I worry that Judge will experience deep slumps and flashes of brilliance, with neither occurring at predictable intervals. Selling high is probably the best play with Judge, especially if you play in a league with Yankees fans.

Jharel Cotton (SP – OAK)

At the time of this writing, Cotton was one of the only rookie pitchers to have two starts. On results, one start was good and one was bad. The truth, as usual, is somewhere in between. Statcast data suggests that Cotton may have been especially unlucky in his first start. While I’m not typically a fan of targeted post-hoc rationalization like this, it is interesting to note that hit probabilities can help us more concretely determine when pitchers are lucky and unlucky in the Statcast era. Fundamentally, Cotton has earned a 10.4% SwStk%, which supports his near 8 K/9 strikeout rate. His walk rate should decline toward 2.5 BB/9. Recent minor league history, as well as a 12.5% SwStk% in 2016, suggest Cotton could be closer to a 9 K/9 pitcher. Cotton’s distinguishing feature is a changeup that is nearly 15 mph slower than his fastball, compared to a league average difference of about 7.5 mph. His arsenal contains a sneaky-good cutter and curveball, both of which give him added credibility as a starting pitcher. If the shaky first outing scared fantasy owners off, go ahead and give Cotton a run in your rotation.

Robert Gsellman (SP – NYM), Amir Garrett (SP – CIN), Antonio Senzatela (SP – COL)

As of Tuesday night, 4/11, Gsellman and Garret each had only one start, Gsellman with poor results but good peripherals, Garrett the opposite. Both are intriguing deep-league streaming options going forward until we get a few more starts to evaluate. Senzatela is a hard-throwing Rockies righty who just completed seven more strong innings at home against the Padres. While his surface numbers look nice, a 94.3% strand rate and .200 BABIP scream, “buyer beware.”

Declining Debutantes

Tyler Glasnow (SP – PIT)

While only one start, Tyler Glasnow was ineffectively wild in his season debut, walking five and allowing five earned runs in 1.2 innings. While one start is typically not enough to judge a player, control has always been Glasnow’s issue. His walk rate has not been below 4 BB/9 at any stop since Double-A in 2015. If Glasnow does figure things out as a starter, he has big upside, but I would not recommend waiting for too many starts for it to click for him this year.

Dansby Swanson (SS – ATL)

Swanson has struggled early with a sub-.200 batting average. However, he has one HR, and his .200 BABIP suggests better times are ahead. A quick glance at Andrew Perpetua’s xStats turns up nothing alarming in his batted-ball skills, especially in such a small sample. Buy into Swanson if anybody is looking to sell.

Andrew Benintendi (OF – BOS)

Entering Tuesday, Benintendi was batting a meager .174, but he did have one HR and one SB. A 3-5 performance Tuesday night put his average back over .250 for the season. Benintendi also famously battled the illness that swept through the Red Sox clubhouse in the first week of the season, so the fact that he has still managed to walk more than he has struck out should tell fantasy owners all they need to know. Sit back and enjoy the ride.



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Andrew Dominijanni is a correspondent at FantasyPros. For more from Andrew, check out his archive and follow him @ADominijanni.