Masahiro Tanaka (Yankees): At the end of June, it looked like Tanaka would battle with Abreu for AL rookie supremacy all the way to the end of the season. He was a legitimate fantasy ace in the first half, with a 2.51 ERA and a 12-4 record. But an elbow injury derailed the 25-year-old's second half, and he did not look like himself when he returned to the rotation in September. Tanaka will be one of the biggest boom-or-busts picks in 2015 fantasy drafts. He could be anything from a 33-start ace to a five-start disaster who spends most of the season on the disabled list with more arm issues.
Billy Hamilton (Reds): Hamilton was among the most polarizing fantasy assets during 2014 draft season, and in the end his detractors were more on point than his supporters. He had trouble getting on base (.292 on-base percentage), and even though he attempted 79 steals, he succeeded on just 56 of those tries. Fantasy owners were expecting around 70 steals, which he could have accomplished if he collected a few more walks and pushed his base-stealing percentage from 71 to over 80. He could make both of those gains next season, but for now, expectations should remain modest, such as 65 steals and 80 runs scored.
George Springer (Astros): Springer took fantasy owners for quite the ride this season. He caused a race to the waiver wire when he was called up in April, and then he was sent back to waivers by impatient owners when he hit .182 with no homers in 55 at-bats that month. But patience paid off in this case, as Springer hit .294 with 10 homers and 25 RBIs in May. He showed plenty of patience at the plate, but his 114 whiffs led to a .231 batting average. Springer's power is undeniable, and his Minor League numbers suggest that he can be a solid basestealer in the Majors. He simply needs to cut down on the K's, and turn a few of those walks back to the dugout into speedy runs to first base. Once that happens -- and it could happen as soon as 2015 -- we will be looking at a fantasy stud.
Dellin Betances (Yankees): Betances picked up just five wins and one save. And he was as valuable to fantasy owners as Phil Hughes, Tyson Ross, Sonny Gray and Hisashi Iwakuma. Yes, Betances was that good. His 1.40 ERA, 0.90 WHIP and 135 K's in 90 innings made him valuable enough to be an every-week option in virtually all leagues. The 26-year-old was dominant from start to finish, and he should be drafted in all leagues next March.
Danny Santana (Twins): Santana hit over .300 in all but one of his five months in the Majors, and he showed developing basestealing skills when he swiped 14 bags after Aug. 1. The 23-year-old's 98-to-19 strikeout-to-walk rate suggests that his batting average could fall next season, but a dip in that category could be offset by improving power skills. It would not be surprising to see Santana hit .300 with 10 homers, 30 steals and 90 runs scored in 2015. Those numbers would make him one of the top fantasy shortstops, so he should be off the board early in 2015 drafts.
Jacob deGrom (Mets): deGrom accomplished so much in 140 1/3 innings this season that he may be the No. 1 sophomore hurler for 2015 drafts. The 26-year-old went 6-1 with a 2.16 ERA and an outstanding strikeout rate in 10 second-half starts. His September numbers were ridiculous, as he held opposing hitters to a .189 batting average en route to a 1.67 ERA and 38 whiffs in four outings. deGrom has enough upside to be a mixed-league ace in 2015, but he can likely be drafted as a No. 3 starter.
Matt Shoemaker (Angels): He went 9-2 with a 1.87 ERA and a .202 batting average against in the second half. Shoemaker pitches for one of the best teams in baseball, and he could be the ace of their staff next season. He will be worth a mid-round pick in mixed leagues.
Yordano Ventura (Royals): For a pitcher that throws so hard, 159 K's in 183 innings is a little disappointing. Control issues led to a 1.30 WHIP, which will drive down his 2015 draft value. If he can improve his control and rack up whiffs at a higher rate, Ventura could be a special pitcher soon.
Javier Baez (Cubs): Baez produced nine homers and five steals in 213 at-bats, but his .169 batting average and 95 K's show that he is not yet a mixed-league asset. If the Cubs can work on this young hitter's approach during Spring Training, he could quickly become an elite middle infielder in the mold of Ian Desmond.
Xander Bogaerts (Red Sox): With 12 homers, 46 RBIs and a .240 batting average in 538 at-bats, Bogaerts was arguably this season's most disappointing first-year player. However, he hit .313 with four dingers in September, and he will be just 22 years old next season. He could make a big leap in year two.
Ender Inciarte (D-backs): The 23-year-old hit .306 with 13 steals in the second half, which could be a preview of a 30-steal season in 2015. He flew under the radar in fantasy circles this season, and he could be a great source of cheap speed in 2015 drafts.
Kolten Wong (Cardinals): With 12 homers and 20 steals in 402 at-bats, Wong has the kind of power and speed that excites fantasy owners, especially when it comes from a middle infielder. He needs to improve his .292 on-base percentage to take the next step, but he should be drafted in all leagues next season.
Gregory Polanco (Pirates): Aside from Springer, Polanco was this season's most-hyped in-season addition. His .235 batting average eventually led the Bucs to go in a different direction, but Polanco's future is still very bright. He could exceed 15 homers and 30 steals next season.
Jake Odorizzi (Rays): Some fantasy owners will look at Odorizzi, see a 4.13 ERA and a 1.28 WHIP and move on to other options. Smart owners will notice that he racked up 174 whiffs in 168 innings, and that he could be a source of 200 K's next season. The Rays have a great track record with young hurlers, and they have plenty of talent to work with in this 24-year-old.
Marcus Stroman (Blue Jays): Stroman was arguably the Blue Jays' best pitcher in the second half, when he posted a 3.38 ERA and a 7-4 record. The 23-year-old is already demonstrating a strong ability to limit free passes, and to keep the ball in the yard, so he could be a very stable mixed-league starter in his sophomore campaign.