"Francis has been working a lot with our pitching coordinator Doug White," Astros director of player development Pete Putila said. "For him, it's mainly being more consistent with his delivery and staying in the zone. He's got big fastball velocity and a big out-pitch, so for him it will come down to consistency out of both the wind-up and the stretch. I think he's got some good experience now and is learning what it's going to take for the next step."
Martes will most likely open the 2017 season with Triple-A Fresno, and if things go well in the early going, he could find himself in an Astros uniform before the end of the year. Should that happen, it would be another big win for Houston's front office, which targeted and acquired Martes from Miami in exchange for Jarred Cosart in 2014, despite the fact he hadn't pitched above the Gulf Coast League.
Tyler O'Neill, OF, Tacoma Rainers (Seattle Mariners)
Coming off a California League-leading 32 home runs in his age-20 season with Class A Advanced Bakersfield in 2015, O'Neill had an even more impressive campaign with Double-A Jackson in 2016. While his 24 long balls with the Generals didn't match his total from the prior year, they ranked second on the circuit behind Mobile's Kevin Cron, and O'Neill displayed an improved approach at the plate, batting .293/.374/.508 in 130 games and walking 62 times -- which matched his career total in 195 contests entering the season.
"Anybody who's been around Tyler will mention some ball he's hit that's the farthest ball they've ever seen hit," Mariners director of player development Andy McKay said. "Obviously the power has always been there, and the ability to control the strike zone has really helped his game. You don't have to look far past what he did in the Southern League at the age he did to see the talent he has. He'll start in the PCL at age 22 and showed well at camp this year."
Not only did O'Neill increase his walks last season, he also continued to lower his strikeout rate -- from 32.9 percent in 2014 to 30.5 percent in 2015 and 26.1 last season. Combining those incremental improvements with a move to the hitter-friendly Pacific Coast League, O'Neill could find himself back in the 30-homer club in 2017. Although if he continues his trajectory with the Rainiers, he may not stay in the Minors long.
Amed Rosario, SS, Las Vegas 51s (New York Mets)
Rosario may be slated for Las Vegas to start the season, but it should be only a pit stop on his way to Citi Field. The Mets' top prospect went from talented youngster to a potential future star in 2016, blossoming into one of the Minor League's top players.
Baseball's No. 5 overall prospect, Rosario tore through the Class A Advanced Florida State League, hitting .309/.359/.442 in 66 games with St. Lucie before moving up to Binghamton. The promotion didn't faze the 21-year-old, who continued to rake at a .341/.392/.481 clip in 54 games with the B-Mets. Overall, Rosario hit .324/.374/.459 with 42 extra-base hits, 71 RBIs and 19 stolen bases in 120 games. The Mets rewarded him with an invitation to Major League camp for the second straight year.
"Obviously, he's coming off a very, very good year," Mets field coordinator Kevin Morgan said. "We hope and anticipate that he'll continue to progress. He performed well in big league camp [this spring]. We just want him to continue to focus on the process, keep him progressing and moving forward."
In addition to his potent bat, Rosario has a strong arm, soft hands and excellent range at short, making him a franchise cornerstone. His build, talent and style of play is reminiscent of another former top Mets prospect, Jose Reyes.