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. Check out last week’s Rookie Report to keep up to date on all the hottest youngsters.

Stats are generally current prior to Tuesday’s games, and, as outlined in week 3, any quoted Statcast numbers are directly from Baseball Savant unless otherwise noted.

View your league’s top available players with My Playbook

Check-In: Andrew Benintendi (OF – BOS)
Way back on April 12th, I expressed little concern for Benintendi’s slow start. While he’s been up and down since his overall .262/.344/.404 line has been somewhat uninspiring. His 12 homers and 9 steals are nicely balanced, but overall underwhelming for fantasy owners who drafted Benintendi as the 112th best player on average. Perhaps most surprising is that the young lefty has neither hit for power nor average. His .262 average and .142 ISO are both career lows and significantly worse than his 118 plate appearances last season. Still, Benintendi’s 10.6% BB% and 17% K% are improvements over last season and very nice marks for a 22-year-old. His .325 xwOBA compared to his .330 wOBA indicate that he has not been unlucky in any meaningful way. Indeed, his 92.2 mph average exit velocity on line drives and fly balls and 5.0% Barrels/batted-ball are pedestrian at best. So, those who expected Benintendi to improve upon his 2016 debut have been overall disappointed, but his excellent and improving approach at the plate gives reason to be excited about his long-term future. Keeper league owners who are already building for next season should consider trading for Benintendi at his low point in value. He also makes for a nice value target in drafts next season, although he is unlikely to be significantly underrated by the industry given his pedigree and passable performance at such a young age.

Derek Fisher (OF – HOU)
After making a nice impression with two homers and a steal in his June debut, Fisher came back up in July and started seeing more playing time, especially following the departure of Nori Aoki before the trade deadline. In 11 total games, Fisher is batting .317/.404/.610 with three homers and the one steal. His minor league track record suggests he may struggle with strikeouts, though his rates of 22% and 19.3% K% at Triple-A the last two seasons have not been particularly alarming. His Statcast numbers are very nice in a short sample so far, especially his 48.4% rate of batted-balls hit over 95 mph, which is 16th best among players with at least 30 batted-balls. With only 31 batted-balls, though, Fisher’s true talent is far from certain. Fisher’s 21 homers and 16 steals in Triple-A this year show that he has little left to prove in the minors. Owners expecting a significant steal total in the majors may be disappointed unless Fisher can post a better success rate than the 59% he has across two levels this season. Perhaps most important for fantasy players, Fisher may not be given much exposure to left-handed pitching down the stretch, even with the Astros holding a big lead in the AL West. Owners in daily leagues should definitely roster Fisher to use against righties and pile up a few homers and steals.

Rafael Devers (3B – BOS)
The sixth best prospect according to the FantasyPros Consensus Rankings and Bobby Sylvester’s personal rankings, Devers gave the Red Sox no choice but to call him up given their league-worst production at the position and his blistering nine games at Triple-A following his merely scorching start at Double-A, all as a 20-year-old. Watching his first few games in the majors and reading scouting reports, it’s clear that Devers’ swing involves a lot of movement and timing, but he also clearly has excellent hand-eye coordination and bat speed. Despite his rapid rise through the minors, he had a very consistent K% near 17%. So far in 27 plate appearances, Devers has launched two homers and hit .417. While he is likely to slump at some point, Devers is the type of elite talent that demands an immediate addition to all rosters.

Yoan Moncada (2B/3B – CWS)
From the Red Sox new major league third baseman, to the man who likely would have been if not for the blockbuster Chris Sale trade. Yoan Moncada was the top prospect on most lists, but unlike Devers, has shown signs of contact problems. A strikeout rate of 30.9% in Double-A and a 28.3% rate in Triple-A, as well as a 42.4% rate in 66 major league plate appearances are of real concern, as is his career .521 OPS. Digging a bit deeper, Moncada’s plate discipline profile is curious. His SwStr% is barely above average, yet his contact percentage is significantly below. His inflated strikeout rate comes, in part, from a very low swing rate and especially low swing rate at pitches in the zone, more than two standard deviations lower than average. When he does swing at pitches in the zone, he is also making contact at a low rate. While we don’t have this level detail for the minor leagues, his talent has always shone through and he has always been better than 30% above league average at each level. Unlike Devers and Benintendi, Moncada’s poor plate discipline make him more difficult to project in the short term. He could put it all together at any time, but he could also go the way of Byron Buxton. The most prudent play for contending redraft league owners is to bench and monitor Moncada, and for keeper league owners to take a shot on acquiring the young Cuban.

Subscribe: iTunes | Stitcher | SoundCloud | Google Play | TuneIn | RSS

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