2017 Prospect Watch: Top 10 left-handed pitchers

MLBPipeline.com will unveil its 2017 Top 100 Prospects list on Saturday, Jan. 28, with a one-hour show on MLB Network at 8 p.m. ET. Leading up to the release, we look at baseball's top 10 prospects at each position.
Exactly half of last year's Top 10 left-handed pitching prospects list graduated off of prospect lists during the 2016 season. The top three -- Julio Urías, Blake Snell and Steven Matz -- all had large impacts, with Urias even pitching in the postseason. Four of the other five are still on the list, including new No. 1 Josh Hader.
Top 10 Prospects by Position
The 2016 Draft has helped replace those graduates, with a trio of first rounders joining the Top 10: No. 12 pick Jason Groome, No. 7 pick Braxton Garrett and No. 6 pick A.J. Puk filling in behind Hader. For the past two years, Urias stood atop this list, with a fair amount of distance between the No. 1 and No. 2 southpaws. While this year's Top 10 is spread out throughout the Top 100, there isn't that kind of separation.
• Scouting reports, grades, stats and video on Prospect Watch
1. Josh Hader, Brewers
Once upon a time, some felt Hader was destined to land in the bullpen. That talk has quieted as his stuff and command of it have improved. Hader has struck out 10.3 batters per nine innings throughout his Minor League career and should be ready to miss big league bats at some point during the 2017 season.

2. Jason Groome, Red Sox
The phenom from southern New Jersey slid a bit in the 2016 Draft because of some off-the-field and signability concerns. Groome will get his pro career started in earnest this year after dipping his toes in with 6 2/3 innings last season. He still has perhaps the best combination of stuff, upside and command of any arm in his class.

3. Braxton Garrett, Marlins
Garrett's first pitch in 2017 will be his first official one as a pro, as the Marlins decided to let him ease in after he signed at the deadline. He has the kind of advanced feel for pitching typically seen in college arms, along with the upside of a high schooler who has yet to fully physically mature.

4. Kolby Allard, Braves
A back issue allowed Allard to slide to the middle of the first round in 2015, much to the delight of the Braves' scouting staff. Atlanta held him back until June last year and he really took off at the end of the season, pitching brilliantly as his Rome club won the South Atlantic League title. The gloves could come off in 2017.

5. Yohander Méndez, Rangers
Signed during the Rangers' international spending spree back in 2011, Mendez was barely on the radar a year ago. But the Venezuelan lefty pitched across three levels of the Minors and made his big league debut, all while showing durability that had previously been elusive, landing him firmly on this (and the Top 100) list.

6. Amir Garrett, Reds
The former college basketball player has always brought size (he's 6-foot-5) and athleticism to the mound and with each year he spends focusing solely on baseball, he becomes a more complete pitcher. With a solid and still-improving repertoire, Garrett is ready to try to get big league hitters out.

7. A.J. Puk, A's
At one point in the running to be the No. 1 pick, Puk was a bit inconsistent during his junior year at Florida. The size and stuff are legit, though, and he did miss bats during his pro debut last summer. If Puk can consistently command the baseball, he has front-line starter potential.

8. Justus Sheffield, Yankees
The second of two first-round picks by the Indians in 2014, Sheffield was part of the package sent to the Yankees in return for Andrew Miller. While he's a bit undersized, he's very athletic on the mound, which should allow him to improve the consistency of his delivery and his strike-throwing, allowing him to reach his mid-rotation ceiling.

9. Sean Newcomb, Braves
There is no question about Newcomb's stuff, leading the Double-A Southern League in strikeouts in his first season with the Braves after coming over from the Angels in the Andrelton Simmons trade. His fastball-curve combination could get big league hitters out now, but he'll need to show better command and control to reach his ceiling as a starter.

10. Stephen Gonsalves, Twins
While he doesn't have an elite-level fastball, Gonsalves does have an excellent three-pitch mix -- four, if you count the slider he's working on -- with a very good idea of how to use it. He gets results wherever he goes, posting low ERAs and batting averages against each step, and he isn't far from seeing how he can fare at the highest level.

Next up
The Indians rolled the dice a bit when they took Brady Aiken in the middle of the first round of the 2015 Draft, given that the former No. 1 overall pick had Tommy John surgery prior to the Draft. He made it back to the mound in 2016 for 46 1/3 innings, but it will be 2017 that will help dictate just what kind of prospect he is at this point.
The Twins decided to develop Tyler Jay as a starter, even though their 2015 first-round pick pitched in relief in college. On the plus side, he made it to Double-A in his first full professional season. But Jay also was shut down with neck inflammation after 83 2/3 innings. He'll have to show his electric stuff will play deep into starts and over the course of a long season.