1) Aaron Blair, RHSP, Braves
There are precious few folks out there that think the Diamondbacks made a smart move in their deal for Shelby Miller. Dansby Swanson was the number one overall pick last year for a reason, and Ender Inciarte is somewhere between an average and well above-average regular in center with five years of team control remaining. That alone seems to be a hefty return for the inconsistent Miller - and that ignores the inclusion of Aaron Blair.
Drafted in 2013, Blair has all of the makings of a solid mid-rotation starter. He has three average or better offerings in his fastball, change-up (his best pitch), and curveball, to go along with solid-average command. Blair is a big and durable groundball pitcher, and he should post average-ish strikeout and walk rates while making 30 starts per year like clockwork. He may not be an ace, but he could be Mike Leake or John Lackey. And, as for 2016, according to Braves manager Fredi Gonzalez, Blair is "a blister, a toenail, a pulled calf away from being in the big leagues. He’s that close for me. … You watch this guy, he’s got pitches, he can navigate through a lineup and you see the mound presence, all the stuff that good major league pitchers have. He has all those qualities."
2) Kendry Flores, RHSP, Marlins
The Marlins starting rotation beyond Jose Fernandez and Wei-Yin Chen is ... uninspiring, at best. It is a group headlined by lapsed prospects and fifth starters, and it will likely see quite a bit of turnover as the season wears on. While he was sent down to Triple-A last week, Kendry Flores is most likely candidate to get the call should an injury or poor performance force the team's hand.
The 24-year-old Flores is purely a back of the rotation prospect; the sort of prospect that inspires the term 'pitchability.' He features a low-90s fastball with good movement and a plus change-up, and he has excellent command and control. His third pitch remains something of a work in progress, as he alternates between a curve and a slider (most seem to believe the former is the superior offering). Flores lacks a true swing and miss pitch, but his ability to spot the ball on the black and change speeds helps him induce a great deal of weak contact, and he won't give up too many free passes. It's not a sexy profile, but he has the ability to contribute average-ish numbers as soon as he finds himself in the Marlins rotation.
3) Tyler Goeddel, 3B/OF, Phillies
The track record for Rule 5 picks is spotty at best, but the Phillies are just one season removed from catching lightning in a bottle with Odubel Herrera. As a rebuilding team with quite a lot of work to do, the team is unafraid to give its youngsters a shot; and the injury to Aaron Altherr and the uninspiring competition offered by Cody Asche and Peter Bourjos means that Tyler Goeddel may reap the rewards.
A supplemental first rounder in 2011, Goeddel offers strong defense at all three outfield spots, as well as an intriguing power/speed combination. He has stolen twenty-plus bases in each of his professional seasons, and began tapping into his above-average raw power last season, with 17 2B, 10 3B, and 12 HR. The 23-year-old has the ability to be a well-rounded player, as he has the tools to hit around .270 with 10 to 15 HR and 20 to 25 SB. Goeddel has yet to play above Double-A, so there will inevitably be some growing pains - but the Philles will give him every opportunity to succeed, lest they have to offer him back to the Rays prior to sending him down.
4) J.T. Riddle, SS, Marlins
I deliberated profiling Mets prospect Matt Reynolds here, as he seems slated to break Spring Training as the team's utility player, and the Marlins feel over-represented in a post discussing prospects. However, Reynolds will be competing for playing time with Wilmer Flores and fellow prospect Gavin Cecchini, whereas Riddle has a fairly clear path to some serious playing time this year.
Drafted as a third baseman in the 13th round of the 2013 draft, Riddle has spent most of his time in the minors as a shortstop, where he is an above-average defender. He profiles as an average or better defender at both shortstop and third base, and he has played a bit of second base, as well (where he has the tools to be well above-average). The Marlins do not have a great deal of depth in the infield (or, at the very least, quality depth), so Riddle's defensive prowess should see him first in-line should the need arise. Offensively, he has a sound, high-contact approach, and the speed and instincts to steal 15-plus bases. He does not have much in the way of power, but he has added some weight to his wiry frame since his pro debut, and could chip in five to ten home runs with enough playing time.
5) Nick Wittgren, RHRP, Marlins
It could be argued that every Marlins is unheralded, by virtue of the fact that this system is wafer this without much in the way of upside. And it is for that reason that Wittgren, a solid relief prospect with closer upside, may well have the most realistic ceiling of any of the team's prospects.
The 24-year-old Wittgren has thrived in his four professional seasons on the strength of a low-90s fastball that induces grounders and weak contact, a solid-average curveball, and nearly elite command and control (he has just 34 unintentional walks in 232.2 IP). He is unlikely to strikeout a batter-plus per inning in the Majors, as he lacks true swing and miss stuff, but he isn't purely a pitch-to-contact type like Brad Ziegler, either. The injury to Carter Capps leaves a sizable hole in the Marlins bullpen, and Wittgren has the best combination of upside and readiness of any reliever in the system.