Hello everyone, and welcome to the first edition of RotoBaller’s new series, Breaking Down Rookie Playing Time in September.

In this article series, I will break down several prospects who have been promoted at some point following the July 31 Trade Deadline, and what you all should make of them for fantasy leagues.

Let's get to it.

• Fantasy baseball trade analyzer
• BvP matchups data (Batter vs. Pitcher)
• PvB matchups data (Pitcher vs. Batter)
• Who should I start? Fantasy baseball comparisons
• Daily MLB starting lineups
• Fantasy baseball closer depth charts
• Fantasy Baseball live scoreboard
• Fantasy baseball injury reports

Top MLB Rookie Performers

Rhys Hoskins (1B, PHI)
Could it be anyone else on top? Hoskins has been nothing short of sensational since his promotion. In 25 games since his call up, he has slashed .307/.419/.750 with 12 homers, a 14.3 percent walk rate and 17.1 percent strikeout rate. And the crazy thing is, his BABIP of .259 suggests he may be unlucky to this point with regards to the batting average (though his HR/FB of 36.4 percent means the home runs are probably going to go down). Hoskins will continue to see regular playing time on a daily basis and should be featured prominently in every fantasy lineup.

Brandon Woodruff (SP, MIL)
In his first start back from his brief hiatus from the majors, Woodruff dazzled once again, holding the Washington Nationals to just a single run on two hits and a walk over seven innings. He struck out eight. Woodruff’s stuff is not the most electric, but he knows how to pitch and should be expected to eat innings moving forward. He is expected to remain in Milwaukee’s rotation throughout the remainder of the season as it’s No. 5 starter.

Robert Stephenson (SP, CIN)
The Cincinnati Reds have already announced plans to shut down rookie phenom Luis Castillo after Wednesday, but they have made no such plans with Stephenson, who sits at only 105 innings this season after compiling 173.2 last year. Stephenson has had some major ups and downs throughout his career, but he looked sharp against Milwaukee Tuesday night (6 IP, 4 H, 1 R, 5 BB, 7 K) and has yet to allow more than two runs in an outing since July. And with his swing-and-miss stuff, Stephenson should provide owners with enough strikeouts to balance out the walks.

Rafael Devers (3B, BOS)
Devers’ slight reduction in numbers has likely disappointed some, but the top Red Sox prospect has still put together a tremendous campaign since being recalled from Triple-A. The young phenom has a .284/.347/.507 slash line with eight homers, an 8.8 percent walk rate and a 25.9 percent strikeout rate, outstanding numbers for a 20-year-old throw into the midst of a playoff chase. Devers has a ton of power upside and has demonstrated he knows how to play to Fenway Park’s dimensions (33.3 percent opposite field rate compared to only a 28.1 percent pull rate) and should remain a strong play in most leagues until he starts to see a major reduction in production.

Lucas Giolito (SP, CWS)
It’s probably still too early to get overly hyped, but Giolito appeared to make some serious strides in honing his incredible repertoire of pitches his last time out when he allowed just one run on three hits and a walk with 10 strikeouts over seven innings. The prospect shine has started to wear off just a bit due to his inconsistent season at Triple-A, but scouts still see a potential front-of-the-rotation arm who just needs to refine his command a bit before he’s ready to reach his upside. And as long as he’s pitching well, he should be a guy to keep an eye on in fantasy leagues.

Worst MLB Rookie Performers

Steven Brault (SP, PIT)
Recalled earlier as a reliever, Brault was given a chance to start against the Chicago Cubs, and it did not go well. He lasted just five innings and gave up three runs on eight hits, two walks and no strikeouts. Admittedly, this was not a bad performance, but it was not great. He really needed to be convincing to lock down a role moving forward this month, and this probably didn’t do him any favors. He has some swing-and-miss potential, but it may be time to start looking at other options as he could be headed back to the bullpen.

Yoan Moncada (2B/3B, CWS)
Moncada has been up for some time now, and it’s safe to say his performance has been disappointing through the majors so far. With a .188/.328/.356 slash line, three homers, a steal, a 15.6 percent walk rate and a 36.1 percent strikeout rate, it’s safe to say Moncada has not yet lived up to the hype. It is not yet time to give up on him. He came back off the DL Tuesday and still possesses a ton of upside. But he is about the highest risk/highest reward play among rookies moving forward.

Derek Fisher (OF, HOU)
Fisher’s first stint in the majors went about as well as anyone could have hoped for. It’s been his second stint that has caused problems. After trading Nori Aoki seemingly to clear up space for one of their top prospects, Fisher has seen his slash line plummet to .219/.322/.371 with four homers and three stolen bases to accompany an 11.6 percent walk rate and 29.8 percent strikeout rate. Like with Moncada, the power/speed upside means Fisher will remain a tantalizing bat to want to own. But until he starts to see his playing time come back and his numbers improve, he is best used only as a last resort in even the deepest of leagues.

Carson Fulmer (SP, CWS)
Fulmer was promoted to the majors more of as a seemingly obligatory move than one indicating his 2017 performance. The once top prospect had a 5.79 ERA and 5.39 FIP at Triple-A this season, and that level of success(?) has carried over into the majors as he has an 13.50 ERA and 13.42 FIP in 4.2 innings so far. Not great. His stuff remains electric, but he likely needs to spend more time in the minors focusing on using it as a reliever rather than being trotted out as a starter. It is clear at this point based on the lack of positive results in two-and-a-half seasons as a starter he is just not cut out for it. Avoid him in all fantasy leagues until further notice.

Amed Rosario (SS, NYM)
Mets’ fans are not going to like seeing their top prospect placed here, but Rosario has not been as advertised since his promotion. His .245/.272/.427 slash line with four homers, four steals, a 1.8 percent walk rate and 27.2 percent strikeout rate underwhelms quite a bit (though the power/speed has been nice). It should be noted he is just 21 years old and carries essentially the weight of a franchise on his shoulder as many have dubbed him the “future” of the Mets. He will be fine long-term, but the short-term concerns leave him as a questionable fantasy target to say the least.

Guys Who Will See the Most Playing Time Moving Forward

Tyler Mahle (SP, CIN)
At all levels of professional baseball this season, Mahle has been the Reds’ most impressive arm. He dominated Double-A, he dominated Triple-A and now he’s been one of the Reds’ best pitchers since his promotion. With a 2.45 ERA and 3.59 FIP over 11 innings of work so far, Mahle has firmly entrenched himself in Cincinnati’s rotation for the remainder of the season. It awaits to be seen whether the strikeouts will be there for him, especially since he is more of a pitch to contact kind of guy, but as long as he’s eating up innings, there is value to owning Mahle.

JP Crawford (SS, PHI)
Crawford debuted in his first MLB game for the Philadelphia Phillies, starting at third base and batting seventh Tuesday. And though he only went 1-for-5, Crawford still should be expected to be a fixture in that Philadelphia lineup for the remainder of the season. He is a young bat who will give the Phillies a fresh look at multiple infield positions including third base, shortstop and possibly second base. And with 15 homers at Triple-A this season and a hot streak that carried him into this promotion, Crawford could be a solid bat to own in some deep/NL-only leagues.

Ozzie Albies (2B/SS, ATL)
Though he has not knocked the cover off the ball, Albies is expected to retain a stranglehold on the Braves’ starting second base position until the end of the season. One of the Braves’ top prospects, Albies has posted a .284/.349/.448 slash line with a pair of homers and stolen bases to accompany a solid 8.5 percent walk rate and 15.4 percent strikeout rate. He possesses some power/speed upside and comes with the added bonus of playing a weak fantasy position in second base. He should be a guy worth owning in all 14+ team leagues.

Luke Weaver (SP, STL)
When a team literally trades an established starting pitcher to make room for a rookie, you know that rookie has some talent. And that’s exactly what happened when the Cardinals traded Mike Leake to permanently add Weaver to their rotation. And it’s safe to say, he has not let the Redbirds down yet as he owns a 2.50 ERA and 3.08 FIP over 36 innings of work for St. Louis so far this season. He is not known for striking hitters out, but he has done his fair share of that this season as evidenced by the 31 percent strikeout rate in the majors. And alongside a mere 7.6 percent walk rate, that makes for a really solid combination for owners in mixed leagues.

Nick Williams (OF, PHI)
The second Phillie to make this list, Williams has earned his fair share of playing time with the way he has hit the ball since his call up earlier this season. His .271/.332/.468 slash line and eight homers are indicative of a guy with plenty of offensive upside, and certainly worth starting if you’re a rebuilding team like Philadelphia. There are several other young outfielders in Philadelphia, but the one who seems the most likely to hold onto his playing time right now is Williams. And as long as that is the case, owners in mixed leagues should consider him to be a solid add.

Guys Who Will See the Least Playing Time Moving Forward

Franklin Barreto (2B/SS, OAK)
It is clear now the Oakland Athletics do not intend to use their top prospect all that frequently. Since being recalled, he has appeared in just two games, and one of those was as a pinch-runner. To be fair, Barreto has shown little in the big leagues to demand playing time, but his minor-league numbers had suggested a possible rebound could be ahead. Alas, he appears to be stuck on the bench for the majority of the remainder of the season unless he makes the most of every opportunity.

Walker Buehler (SP/RP, LAD)
Usually when a guy is promoted as a reliever, playing time is expected to be limited. And though Buehler has a ceiling as high as anybody in this article, his usage as a reliever is going to hurt his potential fantasy value. With that said, Buehler may be counted on to work multiple innings at a time, and has the swing-and-miss stuff to be an electric relief arm. Still, owners need to keep their expectations tempered as he is still just a reliever.

Luiz Gohara (SP, ATL)
Unlike Buehler, Gohara is not going to be a reliever. He would have started Tuesday night had the game not been rained out, but instead he will start on Wednesday. Like Buehler, Gohara has electric stuff, particularly as it pertains to his fastball and slider combination. However, it is not yet known how many starts he will be given. Atlanta’s rotation is starting to look crowded with young arms, and Gohara’s 123.2 innings this season surpassed last season’s career-high mark of 69.2 innings by a very healthy margin, so it’s possible this is just so Atlanta can get an early taste of Gohara for next season. He is an intriguing name to follow, however, and could be a guy worth adding if it looks like he will make more than one start.

Austin Hays (OF, BAL)
One of the most surprising promotions of September, Hays was selected to join Baltimore for the final month of the team’s season. Hays has shot up prospect boards all summer with a head-turning season at High-A (280 PA, .328/.364/.592, 16 HR) and then matching nearly stat for stat the same results at Double-A (283 PA, .330/.367/.594, 16 HR). But Baltimore has a litany of outfielders, and Hays is still just 22 and relatively unproven. They may want to get a glimpse of the future, but with the Orioles just one game out of a Wild Card, they may not want to risk their playoff hopes on the bat of an unproven youngster.

Tyler Glasnow (SP, PIT)
This comes with a bit of a caveat. Glasnow is expected to be recalled by the Pittsburgh Pirates, but not until after Triple-A Indianapolis has completed their postseason run. If that run lasts long, Glasnow may not be up until mid-September, and by that point he might have one or two trips left through the rotation. The upside is there for Glasnow as he has turned in a dandy of a season at Triple-A, but owners would have to wait a little while to be able to reap the rewards.