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Alex Jackson, C, Atlanta Braves (High-A Florida)
Jackson is an athletic, thick-boned man-child. Listed at 6-foot-2, 215 pounds (though looks closer to 225 pounds) with wide shoulders, he is a good target behind the plate. Jackson receives very well with minor flinches that will be ironed out with time, and that is “very well” without considering he has played outfield exclusively as a pro. Moreover, having played the outfield since being drafted sixth-overall in 2014, he has plenty mobility for a catcher. He blocks most balls in the dirt, his throws are accurate and on-line with carry through the target. He commands the field with his quiet confidence and presence, and has a feel for game calling. The Braves scouted this conversion nicely.

Jackson boasts plus-plus raw power, and carries much of it in-game with him, belting nine home runs so far this season. He employs a slightly closed, wide stance and a small load pre-swing. His bat path is linear, with mild leverage and average bat speed. Mild barrel control paired with an aggressive approach have led to a bit more strikeouts and a bit fewer walks than you’d like. All in all these are minor problems given the easy power, despite a below-average hit tool. Jackson profiles as a potential middle-of-the-order run producer thanks to his power potential. —Javier Barragan

Walker Buehler, RHP, Los Angeles Dodgers (High-A Rancho Cucamonga)
Cal League Hitters couldn’t wait to see Buehler, and his 42.9 percent strikeout rate depart for Double-A. In his last start at this level, Buehler continued to exhibit the kind of stuff that puts him on the shortlist for the best starting pitching prospect in the minors. In my look, Buehler worked predominantly from 97-99, topping out at 101. He prefers a two-seam fastball that has late explosion up and away from left-handed hitters. His preferred secondary was a curveball that ranged from 83-87, and flashed good movement and bite. I really like the shape of his changeup, though he only threw one during this outing. Buehler also showed a slider in the high 80s, that has a little more depth, and less velocity than the version he was throwing last season.

Buehler has a fairly clean, up-tempo delivery. At times, he almost seemed to work too fast, and lost his release point a bit. As such, his command is still a bit of a work in progress, relying on pounding the zone instead of hitting spots. If there is a cause for concern, he seems to struggle to locate his fastball glove-side, looking much more comfortable letting his fastball explode away from left-handed batters, and working the inner-half to righties. Also, the secondary stuff can use some refinement. Realistically, anything that is not 100 mph, and around the zone will present serious challenges for an A-ball hitter. But, while he threw some good curveballs and showed the ability to work backwards on a couple of occasions, the pitch still lacks consistent bite and location. Buehler should rapidly ascend the Dodgers system with his stuff as his, but the more he refines his command and secondary offerings, the more his arsenal will rival that of any pitcher in the game. —J.H. Schroeder

Oscar Mercado, OF, St. Louis Cardinals (Double-A Springfield)
As an extremely fast shortstop with a light bat, Mercado was an interesting fringe prospect as recently as a year ago. After posting a .056 isolated slugging at High-A last year and showing questionable glove work, he was downgraded to an extremely fast outfielder with a lighter-than-air bat. The exhaustive list of successful major leaguers fitting that profile is roughly Terrance Gore, which does tend to shuffle a player down prospect lists.

The change of scenery, both to the outfield and to Double-A Springfield, has worked wonders. Mercado already has three home runs on the season, including a grand slam in my viewing. Don't get too carried away, because he has been pretty lucky on fly balls. However, he is driving the ball a bit better despite pulling it less and using more of the field. The real story is how his speed and aggressiveness have transferred to the outfield. Flying Superman layouts into the gaps have become routine early in the season. In my look, he made a sliding stop cut off a double in the gap with the lead off man on first, saving a run. In the tenth inning of the same game, he reached on an infield single, stole second, outran the third baseman to advance on a grounder to third, and scored the winning run in the next at bat. The scorching batting line might cool down, but the speed and defense will keep him relevant a little longer. —Kit House

Ty Buttrey, RHP, Boston Red Sox (Double-A Portland)
I must confess. Occasionally my mind may wander at the end of a 3:30 12-11 minor league game. I am mentally counting how many more guys on base I need to get another Rafael Devers at-bat, or perhaps calculating how fast I will have to drive to get to a bar in Central Connecticut before last call at the end of this fiasco. I make my notes and run my gun on every reliever of course, but the bar for grabbing my attention is going to be a bit higher. Especially in a game that had Rafael Devers almost hitting it out of the stadium in three separate plate appearances. So it’s a little unusual that I was gchatting Craig around 10:15 PM with “Ask Chaz about Trevor Buttrey.” It’s Ty Buttrey (I would have looked this up on the roster eventually), and he got my attention. I can hark back to his being a potential first-round pick in 2012, but falling to the fourth round. We can mull over the slow, unsuccessful path through the minors as a starter. These stories apply to many, many Double-A pen arms though. Buttrey might not be in Double-A for long though. Something appears to have clicked for him and he looks mighty close to major-league-ready. 97 on my gun is a good way to get my attention. Sure, velocity is up, but Buttrey’s velocity comes easily. He’s just playing catch with his backstop. His slider is a relatively new offering, but flashed plus with hard, downer action and he can spot it for a strike when he wants. The change looked like the changeup of a dude that got moved to the pen in his first inning of work, but showed as a low-80s split in his second. The mechanics are a little herky jerky, and the command profile is another reason he’s in the pen now, but Buttrey has bat-missing stuff you don’t see past ten o’clock at most minor league games. —Jeffrey Paternostro

Drew Jackson, SS, Los Angeles Dodgers (High-A Rancho Cucamonga)
The Dodgers acquired Jackson from the Seattle Mariners this spring in exchange for starting pitching prospect Chase De Jong. Jackson immediately climbs to the top of the list of shortstop prospects in the Dodgers system. Jackson’s carrying tool is his defense, most notably a plus-plus arm. The former Stanford Cardinal made several plays from deep in the hole look routine in my look this week. In addition to a strong arm, Jackson possesses above-average athleticism, good quickness, and instincts. Several times during his series against Lake Elsinore, he made subtle pre-pitch positional adjustments based on the pitch selection, and catcher set-up.

After a strong-start to 2016 at the plate, Jackson struggled in the second-half. He’s made some changes to his swing, most notably strengthening his front side, and not sliding into the pitch as much, which should allow him to make more consistent, and harder contact. He still has a bit of a flat bat path, making him more effective on pitches up in the zone. There’s a lot to like about his offensive profile. Jackson handles velocity well, recognizes and hits spin, and has a good idea of the strike zone. He also uses the whole field, hitting the ball where it’s pitched. Jackson reminds me a bit of a young Brandon Crawford defensively. Like Crawford, I think Jackson is the kind of athlete, and personality, that will continue to develop at the plate. An elite defensive shortstop that offers non-zero production at the plate is a valuable commodity, and Jackson has the potential to be that and more. —J.H. Schroeder

Luis Guillorme, SS, New York Mets (Double-A Binghamton)
When watching Guillorme play, it does not take long at all to see that he is a special defensive player. He possesses strong, fast hands (Exhibit A) with a plus arm, quick release, and excellent range. His defense alone should allow him to make a big-league roster.

The difference between a bench and regular role will be his offensive development, and Guillorme is enjoying a breakout season at the plate thus far. Through his first 101 plate appearances, he is slashing .326/.400/.382. He has never hit for power, and at 5-foot-9 and 190 pounds, don’t expect that to suddenly change. Nor will he impact the game on the basepaths. However, he has displayed a potential average hit tool in Double-A with decent plate discipline. Yes, an unsustainable BABIP of .397 suggests some regression going forward. Nonetheless, due to his strong hands, impressive hand-eye coordination, and good bat control, he consistently makes contact to all parts of the field.

Amed Rosario is certainly a much more exciting prospect. He has a more athletic frame, runs well, and is noticeably better at the driving the ball. While Rosario will likely become the Mets' starting shortstop in the near future, Guillorme's stock is on the rise and should reach the majors at some point in 2018. —Erich Rothmann

Conner Menez, LHP, San Francisco Giants (High-A San Jose)
A 14th-round pick last June out of a small NAIA school in the organization’s backyard, Menez has an athletic, projectable frame, with some length to his limbs and solid physicality. The delivery is up-tempo and fluid through a short leg kick that really builds momentum well, helping him drive hard down the hill. I was impressed with his balance, though he can get too quick with the whole thing and lose his timing for spells. There’s a bit of violence in the delivery, but his foot strike is pretty consistent and he gets over his front side effectively.

The fastball worked 90-93 all night, holding its velocity through six innings and showing crisp two-way action. He cut it in on righties effectively for most of the night, and a two-seamer bore in on lefties with above-average horizontal movement as well. His command wavered through the middle innings as he worked in and out of the stretch, but with some refinement and consistency this pitch can play to solid-average, with another half-grade possible if he were able to tick the velocity up in a shorter burst. The slider was his best secondary, with two-plane movement and late bite at its best. It flashed plus in the 81-83 range, and made for some uncomfortable left-handed swings in particular. His changeup at 78-81 was an uneven affair, with a flatter plane and some show, though with enough velocity separation and hints of turned-over fade to project fringe-average future utility. He dropped in a handful of get-me-over mid-70s curves in the middle innings, with a rolling shape and limited utility.

Menez is an interesting little under-the-radar arm, with a solid foundation for situational relief underpinning a profile that has just enough raw material to envision a future at the back of a rotation if he maxes out the fastball command and changeup projection. —Wilson Karaman

A.J. Puckett, RHP, Kansas City Royals (High-A Wilmington)
Puckett, a second-round pick out of Pepperdine last June, is perhaps the best hope for a fast-track arm in the Royals’ system. At 6-foot-4 and 200 pounds, Puckett has a solid base; he works from a high-three-quarters slot and has a clean delivery. His straight, heavy fastball sits 90-91 mph, but he can tick it up at times and touched 94 in the outing. His command of the heater was loose early on but he settled in as the outing wore on. His changeup is capable of being a plus pitch at 81-83 mph and he showed good command of it, relative to the fastball. This led to Puckett falling behind in many counts early on in his outing, which meant he was unable to work the changeup in as often as he would have liked. Puckett won't succeed as a starter unless he develops a go-to third pitch, however, and he has been working on an 11-5 curveball with some sharp bite on it. The curveball sits between 74-76 mph and showed some swing-and-miss promise. The curve will be a major point of emphasis for him for the rest of the season.

There's no question that Puckett's fastball and changeup could get him to a major league bullpen as a swingman, but if he develops the curve, which he seems truly committed to working on, he profiles well as a back-end starter. —Victor Filoromo

Patrick Mazeika, C/1B, New York Mets (High-A St. Lucie)
It’s not likely that you’ll find this name on any top prospect list, but what Mazeika is doing to opposing pitchers in the Florida State League is worth taking note of. In a four-game series between Bradenton and St. Lucie, his hit tool stood out more than any others, just as it has all season. With great barrel control and an easy left-handed swing, it is no surprise that he is currently slashing .360/.424/.593 through 24 games; ranking second in BA, fourth in OBP, first in SLG, and second in OPS. An eighth-round pick out of Stetson in 2015, Mazeika has produced at every level he’s been at thus far (and he’s had to) and one can assume much won’t change moving forward with his advanced plate discipline and coverage. Furthermore, he showed strong lower half usage and leverage in his swing to go along with slightly above-average bat speed, projecting to be an average power threat long term.

Mazeika is athletic enough to stick behind the dish and was comfortable picking pitches out of the dirt, but his below-average arm strength and crude blocking ability will likely force him to first base. His high baseball IQ should make the transition relatively smooth, and he has the tools to be solid at the cold corner. As a 23-year-old, Mazeika’s success isn’t going to mean much until he continues to do the same at the upper levels. —Josh Turner

Brandon Leibrandt, RHP, Philadelphia Phillies (Double-A Reading)
Listed at 6-foot-4, 190 lbs, the Phillies 24-year-old left-hander has an athletic, lanky frame with some room for added strength. Leibrandt missed most of 2016 recovering from shoulder surgery and was making his fifth career Double-A start on May 7th. Leibrandt has a fairly easy, rhythmic, hands-over-head delivery and four-pitch mix (fastball, slider, changeup, curveball). His fastball was 87-89 showing cut at times and he struggled to command it. The slider was 83-86 with long, 1/7 action showing average potential. Leibrandt got on top of his changeup at 80-82 with short, straight, downward-breaking action. The pitch was inconsistent and fringe-average overall. The curveball was fringe at 73-75 that he casted to the plate and lacked bite. It was Leibrandt’s shortest outing of the season only making it 2 2/3 innings after allowing seven earned runs on five hits with three walks and one strikeout. The overall stuff and lack of command this outing wasn’t anything particularly encouraging. However, Leibrandt does show flashes of a serviceable four-pitch mix and has shown a history of above-average control, although it was not on display this outing. It’s worth following to see if Leibrandt continues to regain strength returning from surgery and is able to add a tick of velocity on the fastball and refine some of his secondaries to possibly become a late bloomer and develop into something more than just a solid starting organizational arm and possibly a no. 5 starter or up & down spot starter in the future. —Chaz Fiorino

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That is a stretch to praise the Braves for their scouting on the Alex Jackson conversion. I don't know if anyone in baseball doesn't know that he was drafted as a catcher.
No one is implying that he wasn't a catcher before or that other teams didn't know. It was about understanding (or taking a chance) that he'd be able to convert back after multiple years away from it.
It should also be an indictment on the Mariners system, as Jackson was never given a chance at catcher even after it was clear a shift to the outfield wasn't going to allow him to move quickly as the team hoped.
Consider me very skeptical that a guy with a 4 BB% and 25.4 K% is a middle of the order bat. I personally think he'll be lucky to be a 1.5 WARP regular
It comes as a major surprise, and a pleasant one, to see the names of Alex Jackson and Ty Buttrey mentioned after both had been discarded onto the post prospect trash heap.