Kolek, the second overall pick in the 2014 First-Year Player Draft, is an imposing 6-foot-5, 260-pounder from Shepherd, Texas. In 22 innings with the Gulf Coast League Marlins, the 19-year-old was 0-3 with a 4.50 ERA. The Texan, who has tremendous upside, struck out 18 and walked 13 in his first nine professional games.
In terms of raw ability, Miami feels Kolek has top-of-the-rotation potential. He turned 19 in December, and he may start 2015 at Class A Greensboro.
The Marlins spent considerable time evaluating Kolek in high school.
"We didn't really see any red flags," vice president of scouting Stan Meek said on Draft Day. "We spent a lot of hours on him. We helped the economy in Shepherd, Texas."
Before sending Kolek home for the offseason, he threw some more innings in the instructional league in September and early October. The power arm is certainly there. What the team wants is for Kolek to improve other aspects, like fielding his position and holding runners. He is also fine-tuning his delivery, striving to create more of a downward plane for his fastball.
"I'm learning to just calm down," Kolek said in October. "Whenever I used to throw, I would just rear back and see how hard I could throw it. Now, things have changed a bit. Here, the hitters are smarter. It kind of just brings you down to earth and makes you appreciate throwing the ball to where you want to throw it."
Realmuto, 23, was Miami's third-round pick in 2010. A former football and baseball prep star in Oklahoma, the catcher enjoyed a breakout season in '14. In 97 Double-A games, he batted .299 with a .369 on-base percentage and a .461 slugging percentage.
Realmuto, who projects to open at Triple-A New Orleans, saw limited action with the Marlins, appearing in 11 games and hitting .241 with a double, triple and nine RBIs in 29 at-bats.
Miami feels Realmuto may become its everyday catcher in another year or two.
The annual ranking of baseball's Top 100 Prospects is assembled by MLBPipeline.com Draft and prospect experts Jonathan Mayo and Jim Callis, who compile input from industry sources, including scouts and scouting directors. It is based on analysis of players' skill sets, upsides, proximity to the Majors and potential immediate impact to their teams. The list, which is one of several prospect rankings on MLBPipeline.com's Prospect Watch, only includes players with rookie status in 2015. Team-by-team Top 30 Prospects lists for 2015 will be unveiled in March.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.