MIAMI -- Two years ago, Tayron Guerrero was one of the Marlins¡¯ most promising relievers in Spring Training, dominating with a 100-plus mph fastball and showing glimpses that he could be a potential closer.

But after dealing with wildness in 2019, Miami designated the 6-foot-8 right-hander for assignment on Monday.

The decision is telling because the Marlins are in the market for bullpen help. But they still parted with an experienced hard thrower who is not eligible for arbitration until 2021.

Marlins president of baseball operations Michael Hill addressed Guerrero¡¯s situation in a conference call on Tuesday, and he also sent a signal to what the organization is prioritizing.

¡°Obviously, this past season, [Guerrero] had troubles with commanding the strike zone and resorted back to an incredibly high walk rate,¡± Hill said. ¡°For a number of our young relievers, they need to get better. They need to throw more strikes, because you can¡¯t defend a walk.¡±

Guerrero is the case in point. In 46 innings, the 28-year-old averaged 8.41 K/9 and 7.04 BB/9. The decline in command came after he averaged 10.55 K/9 in 2018 and 4.66 BB/9.

¡°We saw over the course of the 2019 season our bullpen issues and our staff in general,¡± Hill said. ¡°We issued entirely too many walks.¡±

As a whole, Miami¡¯s bullpen had a 4.37 BB/9 rate in 2019, which was tied with the Pirates for the second most in the Majors. Only the Red Sox (4.38 BB/9) issued walks at a higher rate.

For the Marlins, it wasn¡¯t necessarily a case of the bullpen being overused. In all, the ¡®pen logged 556 1/3 innings, which was 23rd overall. On the flip side, the Marlins¡¯ starters worked 888 innings, tied with the Cubs for the seventh most.

The challenge in free agency is finding veteran relievers who have not only performed but are also strike throwers.

One potential candidate is free-agent right-hander Dellin Betances, a four-time All-Star with the Yankees. Many Marlins executives have ties to the Yanks, which gives them plenty of history with Betances, who could be a reclamation project in Miami. But Betances appeared in just one regular-season game in 2019, as he dealt with a right shoulder impingement and then a partial left Achilles tendon tear.

Betances had success in 2018, posting a 2.70 ERA in 66 appearances, with a K/9 rate of 15.53 and a BB/9 rate of 3.51. And like Guerrero, Betances is listed at 6-foot-8. For tall pitchers, repeating their delivery can be a challenge.

Part of the problem for the Marlins in 2019 was that their bullpen was loaded with inexperienced hard throwers, many of whom labored tossing strikes. Per Statcast, on all fastballs, Miami¡¯s relievers averaged 94.5 mph, the highest in the Majors. The Mets were next at 94.2 mph.

Guerrero¡¯s 98.9 mph average fastball topped all big league relievers with a minimum of 500 pitches. On the Marlins, five other relievers had their fastballs average at least 95 mph -- Ryne Stanek (97.6), José Ureña (97.1), Jeff Brigham (96.6), Nick Anderson (95.9) and Adam Conley (95.3).

Anderson was with the Marlins during the first half of the year before being traded to the Rays on July 31.

Moving forward, Miami is looking for more than merely velocity. The Marlins' targets must also show command, and they will give bullpen candidates a shorter leash if they aren¡¯t performing.

¡°When we win more games and compete for championships, guys are going to have to command the zone and come in and do their part in getting outs,¡± Hill said. ¡°Guys given an opportunity have to take advantage of that opportunity. If they aren¡¯t able to take advantage of that opportunity, we¡¯ll find someone who is.¡±