MIAMI -- The Marlins on Friday purchased the contracts of four Minor Leaguers who are getting closer to being big league ready: right-handers Luis Castillo and Drew Steckenrider, along with infielders J.T. Riddle and Austin Nola.
By adding these four to the 40-man roster, Miami protected them from next month's Rule 5 Draft.
Friday is the deadline for teams to add to their rosters players who have become eligible for the Rule 5 Draft, set for Dec. 8 on the final day of the Winter Meetings.
Those eligible to be selected include any player not on the 40-man roster who signed in 2012 at 18 years old or younger or in '13 at 19 or older.
According to MLBPipeline.com, Castillo is Miami's No. 5 prospect, and Riddle is rated 11th.
The Marlins 40-man roster is now at 36, after they claimed left-hander Elvis Araujo off waivers from Philadelphia on Friday.

By purchasing the contracts of just four players, the Marlins now may lose three other players ranked in the organization's Top 30. MLBPipeline.com rates outfielder Austin Dean sixth, lefty Raudel Lazo 28th and right-hander Jose Adames 29th. All three could be tempting for another club in the Rule 5 Draft.  A team that makes a selection during the Major League phase of this Draft must pay $50,000 and commit to carrying the selected player on its active roster through the entirety of the following season. A selected player can be offered back to the original club for $25,000.
Castillo and Steckenrider most likely will open 2017 at Triple-A New Orleans, but they both could be in the big leagues at some point in June.
Castillo is coming off a strong season. The right-hander was named the Florida State League Pitcher of the Year after dominating at Class A Advanced Jupiter.
The 23-year-old Castillo started off at Jupiter before being promoted to Double-A Jacksonville. He combined for an 8-6 record with a 2.26 ERA in 131 2/3 total innings. His fastball velocity reaches 97 mph, and he projects to being a solid No. 3 big league starter.

The Marlins actually had lost the services of Castillo when he initially was part of the seven-player trade between the Marlins and Padres on July 29. That deal sent right-handers Carter Capps and Jarred Cosart, plus first-base prospect Josh Naylor and Castillo, to San Diego for right-handers Andrew Cashner and Colin Rea, plus Minor Leaguer Tayron Guerrero.
But after Rea injured his throwing elbow in his only start with the Marlins, Miami and San Diego revised the trade. Rea was sent back to the Padres, and Castillo returned to Miami.
Riddle is a left-handed hitting infielder who may wind up at third base. The 25-year-old combined to hit .276/.326/.366 with four home runs and 53 RBIs in Double and Triple-A in '16. He also could go to the outfield or perhaps be a super utility player.

Steckenrider is a hard-throwing reliever who gained a lot of attention at the Arizona Fall League, striking out 15 in 13 innings. He likely will open at New Orleans, but could be a factor in the bullpen during the season for the Marlins.
Nola is the brother of Phillies right-hander Aaron Nola. The 26-year-old infielder has spent parts of the last two seasons at New Orleans, and he's played in 566 Minor League games.
The Marlins did not protect several other prospects who have been part of the organization for a number of seasons. Infielder Avery Romero and outfielder Dexter Kjerstad will be available in the Rule 5 Draft.