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. So far I have avoided repeating any players, so check out last week’s Rookie Report to keep up to date on all the hottest youngsters. As I have begun to exhaust all the interesting rookies, starting with Week 4, I will be revisiting some of the more impactful performers.

This week I also feel compelled to add a point of clarification on Statcast data. As I outlined in the preseason, Statcast is still pretty new. As such, there is ongoing discourse in the public sphere about whether reported measurements, such as exit velocity, have systematic biases that vary from park to park. A first look came about at Baseball Prospectus, and Andrew Perpetua has discussed and employed similar corrective methods in his excellent xstats.org resource. Without official comment from those at MLBAM who publicize Statcast, we have no real way of knowing whether these properties are stable. Simple calibration tweaks could be made at any time, rendering third-party adjustments obsolete without warning. Therefore, when I cite Statcast data in the Rookie Report, which I will frequently do, I will be citing “raw” numbers from Baseball Savant unless otherwise noted. Some more interesting new resources are xwOBA and xBA available directly via Baseball Savant. In principle, these take a similar, perhaps less complex approach than xstats.org, in that they do not appear to factor in horizontal angle, ballpark bias, temperature, or running speed. While these new metrics derived from Statcast are very exciting, I still advise an approach anchored on more established advanced stats that folds in the very cutting edge numbers cautiously.

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Starring

Taylor Motter (SS – SEA)
When Jean Segura hit the disabled list with a hamstring strain, Taylor Motter started to see every day playing time at shortstop. Segura just came off the DL Tuesday and seems locked in as the starter. However, Motter forced himself into the conversation in Seattle by hitting five HR and stealing two bases since Segura’s injury. He has a bloated 29.4% HR/FB rate, but only a .255 AVG. Motter ranks in the top 10 of average exit velocity at 94 mph, and his .289 expected batting average (xBA) suggests he has been a bit unlucky in that department. Despite being relatively old for his levels, Motter was always a solid power/speed threat in the minors. While he could be a 15-15 hitter given full playing time, Motter will not continue to slug over .600, or even .500, and his average will probably stay around .250. The good news for fantasy owners is that the departure of Leonys Martin opens up two outfield positions for rotation between Motter, Jarrod Dyson, and Cuban rookie Guillermo Heredia. If Taylor Motter continues to hit, he will continue to see time.

Manny Pina (C – MIL)
Let’s start with the obvious: Manny Pina is a part-time catcher. Part-time catchers are rarely exciting in fantasy baseball. However, Pina plays behind Jett Bandy and has recorded a nearly identical number of plate appearances as Bandy thus far in 2017. In deep leagues, especially deep two-catcher leagues, any catcher with a pulse is of note. As it turns out, Pina has been pulsating so far, with a .419 AVG and 1.096 OPS with one HR. Anyone batting .419 is likely to have an inflated BABIP, and Pina’s sits at .447. He has hit, to date, 37.8% line drives, but his average exit velocity on line drives and fly balls is only 91.1 mph. To his credit, Pina is making contact at a 92.2% rate, well above his career 82.7% mark. Pina, age-30, has been good at Triple-A the past two seasons but has never hit double-digit homers in any season, majors or minors. With Jett Bandy also hitting for power, and Andrew Susac lurking in Triple-A, even the most desperate fantasy owners should be wary of investing much of anything to chase this hot streak.

Jose Martinez (OF – STL)
Compared to fellow 6’7″ outfielder Aaron Judge, Jose Martinez receives almost no attention. Martinez brings a solid track record of contact – a career .294 minor-league hitter with a 15% K% – but a modest .765 OPS. In 51 major-league plate appearances, Martinez has delivered on the promise of plate-discipline with an 8.3% BB% and 8.3% K%. A BABIP-fueled .375 AVG has been the bulk of his fantasy value in his brief major-league career, as he has only one homer and one steal. His xBA stands at .326, which is in the top 10 of hitters with more than 20 at-bats. An 86.9 mph average exit velocity does not portend a power outburst, either. Despite his imposing stature, Jose Martinez does not provide much fantasy excitement beyond an empty batting average, especially in his current bench/utility role.

Koda Glover (RP – WSH)
Spring Training was a bit of a roller coaster ride for Koda. At one point, he appeared to be the favorite for the Nationals closing job, eventually losing out to Blake Treinen. A result of Treinen’s early struggles, Glover now seems to be the primary setup man behind Shawn Kelley, or perhaps the short end of a two-man committee. The Nats seem cautious not to overuse Kelley, so Glover could see his share of save opportunities, with two saves already banked. Glover primarily features a mid-nineties fastball and a hard slider. This repertoire has earned him a 44.4% GB% and 6.23 K/9, underpinned by a 9.2% swinging strike rate (SwStk%). So far this year, Glover has shown better control, dropping his walk rate to 1.04 BB/9 from 3.2 in 2016. His results have been a bit better in 2017, pitching to a 4.15 ERA, somewhat inflated by a two earned run appearance in a wild Coors game Tuesday. Given that elite strikeout relievers tend to have strikeout rates over 10 K/9 and SwStk% above 14%, Glover might not be the type of reliever that helps in Ks, ERA, and WHIP sufficiently to be valuable without getting saves, but enough questions remain in the Nationals bullpen that Glover is worth keeping tabs on as the season progresses. In leagues that count holds, he continues to be an option with a solid path to high-leverage situations.

Sputtering

Cody Reed (SP – CIN)
Cody Reed showed some nice signs early last year during his midsummer stint in Cincinnati, but in the end, his 7.36 ERA and 1.80 WHIP in 10 starts painted a bleak picture coming into 2017. His 4.32 xFIP, on the strength of 8.12 K/9 and a solid 52% GB%, hinted at something more promising. The Reds, if nothing else, had open positions on their major league pitching staff, so Reed figured to get a chance to live up to his modest prospect pedigree. So far, in four relief appearances and one start, it has not gone well. Perhaps as expected coming out of the bullpen, Reed has ramped up his strikeout rate to 9.9 K/9 but has an ugly 8.1 BB/9. He has generated a stellar 65% GB% and 15.9% SwStk%, and according to at least one reliable account, has good stuff by movement, velocity, and whiffs. Reed has yet to give up an earned run out of the bullpen but got shelled for seven in his lone start. It remains to be seen if Reed gets another turn in the rotation or is moved back to the bullpen. Because the Reds’ pen is so crowded, deep-league fantasy owners should root for Reed to remain in the rotation – and hope for improved results from his three-pitch arsenal – but leave him on the waiver wire for now.

Jacob May (OF – CWS)
May earned the White Sox starting centerfield job out of Spring Training but has struggled to the tune of a .033 AVG with a .180 OPS and a 36.1% K%. Lately, he has found himself more frequently on the bench in favor of Leury Garcia. Never considered a major hitting prospect, May’s calling card is speed. He has minor league season stolen base totals of 24, 37, 38, and 19, although his stolen base success rate of 75% is not stellar. His minor league track record suggests he won’t continue to strike out at quite this rate, although his .087 xBA suggests he is feeling overmatched at the moment. In the best case scenario, if he can stabilize his approach, May could deliver speed-only value similar to 2016 Mallex Smith.

Frankie Montas (RP – OAK)
At this point, the conventional wisdom seems to be that Montas profiles as a high-leverage reliever, despite a seemingly sturdy frame. Like the aforementioned Koda Glover, Montas primarily works with a mid-nineties fastball and a slider which itself gets 30.4% whiffs. Overall Montas has an 11.7% SwtStk%, which, on average, would portend closer to 9 K/9 than his current 7.59 mark. In only a 10.2 IP sample, though, this is the difference of one or two more strikeouts. Health has been a major concern for Montas – he had a rib removed last year – but his scouting profile and early results remain intriguing. It’s possible the Athletics still believe he can be a starter, but I am more interested to see if Montas can work his way up the leverage ladder in a talented but aging Oakland bullpen.

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