LAKE BUENA VISTA, Fla. -- After trading away one outfielder in a deal that was criticized for the lack of impact prospects it netted, the Marlins get higher marks for the trade of a second outfielder, completed on Thursday afternoon.
Miami's trade of Giancarlo Stanton to the Yankees on Monday yielded only one prospect who cracked its Top 30 Prospects list, but the organization improved its farm system in the haul it brought in for Marcell Ozuna. Two of the prospects, outfielder Magneuris Sierra and right-hander Sandy Alcantara, were in the Cardinals' Top 10. Right-hander Zac Gallen was just outside of it. All three will be firmly in the Marlins' Top 15.
• Trade finalized: Ozuna dealt for Cardinals prospects
The fourth prospect headed to Miami, 23-year-old lefty Daniel Castano, was a New York-Penn League All-Star in 2017, when he went 9-3 with a 2.57 ERA in 14 starts for State College, recording 81 strikeouts and 13 walks.
After getting Jorge Guzman from the Yankees in the Stanton deal, the Marlins added another power arm in Alcantara. Like Guzman, Alcantara can get it up to triple digits on a regular basis, just like he did during the Arizona Fall League's Fall Stars Game. He can maintain his velocity deep into starts and late in the season. Alcantara's second-best pitch is his changeup, which he'll throw around 90 mph and will flash above-average. The 22-year-old will show a feel to spin a breaking ball, but his curve and slider often blur into each other and they lack consistency.
While Alcantara does have as much easy velocity as perhaps anyone in the Minors, and as much upside as any arm in Miami's system, the one thing that causes a pause is his struggles with command and control. It's not just the walks (3.7 BB/9 in the Minors), but his command in the zone has caused him to be more hittable than he should be, especially given his power stuff. Alcantara gave up 9.0 hits per nine in Double-A last year, and while he generally got good reviews for his work in the AFL (he came in as MLBPipeline.com's No. 24 prospect there), he had some of the same inconsistencies that have plagued him elsewhere. He did make his big league debut last year, pitching out of the Cards' bullpen and touching 99 mph, with some feeling that might be his eventual home.

If the Marlins were looking for a strong defender to patrol the big center field in Marlins Park, they may have found their man in Sierra. Like Alcantara, Sierra jumped from Double-A to make his big league debut in 2017, and he went 19-for-60 (.317) in his first taste of the highest level. Sierra is a plus defender, one with tremendous instincts and range, not to mention a plus arm.
At the plate, Sierra has shown a knack for making consistent contact, albeit without much power. He did improve his walk rate a bit in 2017, something he'll need to continue to do to settle in as a table-setter atop Miami's lineup. For now, seeing Sierra contribute mostly with his defense while settling into the bottom of a big league lineup might make the most sense.

Gallen gives the Marlins a third prospect in this deal who should contribute in the big leagues in 2018. While Alcantara has a really high ceiling, Gallen's high floor is what makes him an interesting pitching prospect. The 2016 third-rounder out of the University of North Carolina pitched his way across three levels, up to Triple-A in his first full season of pro ball. He proved to be durable, compiling 147 2/3 innings along the way, and lived up to advanced billing in terms of his command and control, walking just 2.1 per nine for the year.
In terms of raw stuff, Gallen doesn't jump off the page. But he does an excellent job of throwing his low-90s fastball down in the zone with good life. Gallen's changeup has the chance to be a plus offering, and while he throws his cutter/slider too much at times, it's effective and gives him a third at-least-average pitch to attack hitters with. It's not the type of stuff that says "front-line starter," but he does seem to be a safe bet to reach his potential as a No. 4 or 5 starter. And Gallen should be able to do that in the very near future.
Castano was selected by St. Louis in the 19th round of the 2016 Draft out of Baylor University, and he is 11-8 with a 3.82 ERA in 26 career appearances (25 starts).
Detractors might argue the Marlins didn't manage to wrest one of the Cardinals that appear on the overall Top 100 Prospects list in this deal, perhaps a valid point given the year Ozuna had in 2017. But there is no question this deal added depth to a system in need of a talent infusion.