PITTSBURGH -- When Trevor Williams saw Ben Cherington’s name flash across his phone on Friday afternoon, he knew there were only two reasons the Pirates general manager could be calling.

So Williams wasn’t surprised when Cherington informed him that he’d been designated for assignment, even if the thought of such a move would have seemed unfathomable at this time two years ago. But Williams has struggled through injury and inconsistency the last two seasons, and the Pirates needed a roster spot as they faced Friday’s deadline to protect eligible prospects from the Rule 5 Draft.

• What is the Rule 5 Draft?

The Pirates designated Williams and corner infielder/outfielder José Osuna for assignment to make room on their 40-man roster for infield prospect Rodolfo Castro and right-hander Max Kranick. Osuna is likely going to pursue an opportunity to play in Asia, Cherington said, while the Pirates essentially expedited the process of cutting ties with Williams after deciding they would not tender him a contract for next year.

“I had a chance to talk to Trevor today and just express to him how much we appreciate who he is as a person, his professionalism and what he's done for the Pirates,” Cherington said Friday night. “He has been a good and reliable pitcher for the Pirates. He is certainly a really good guy. We’ll be rooting for him.

• 40-man deadline: Which prospects made it?

“I’m sure he’ll continue to work hard to make the adjustments he needs to make to be competitive and successful at the Major League level. I won’t be surprised if he does that, but we weren’t in a position where we could commit to that right now at this point in the offseason.”

Williams went 14-10 with a 3.11 ERA in 31 starts in 2018, and his incredible finish -- including a 1.29 ERA over his final 13 starts --helped him earn the Steve Blass Award as the Pirates’ best pitcher that year. But his fastball became less effective over the past two seasons, especially after an oblique injury that interrupted his ’19 campaign, and he posted a 5.60 ERA and 1.46 WHIP over his past 37 starts.

Williams’ full-season salary for the 2020 season was set at $2.825 million, and he would have received a raise this winter during his second trip through the arbitration process. Now, he’ll either be claimed by another team or become a free agent.

"Not surprised, but I understand the reasoning and I get it. It's 'what have you done for me lately?' and I haven't been producing at the level that I know I'm able to. So, that was really it,” Williams said. “For me, it’s [figuring out how] to get back to how consistent I was prior to the injury. … I know it’s there, and I get flashes of it. I need to remind myself that I’m a good Major League starting pitcher.”

Williams has been an exemplary teammate and member of the Pittsburgh community since the Pirates acquired him from the Marlins in October 2015. Even after being cut loose, the 28-year-old posted on Twitter encouraging fans to donate to the club’s “Friendsgiving” charity drive. He said his most memorable moment in Pittsburgh was his debut -- an unforgettable moment he shared with Jackie, his oldest son, and his father, Richard -- and he was most proud of the bonds he forged with his teammates.

“There was a core group of us that grew up together the last couple years, and the opportunity to play with those guys and compete with those guys is something that I'm really going to remember and cherish,” Williams said.

Meanwhile, Osuna struggled to lock down a role in Pittsburgh since making his debut in 2017, and Will Craig is a similar player capable of manning the same positions. Osuna was at his best as a pinch-hitter with power, but there was less need for that type of player with the designated hitter in the National League this past season. Osuna’s interest in playing overseas sped up the Pirates’ decision to part ways with the arbitration-eligible 27-year-old.

The Pirates needed to clear those two spots on the roster to make room for Castro and Kranick, who will end the year on the Pirates’ 40-man roster after spending the summer at the alternate training site camp in Altoona, Pa.

• Pirates Top 30 Prospects

The Pirates left a handful of interesting prospects unprotected, but they aren’t necessarily at risk of losing them in the annual draft held on the final day of the Winter Meetings, which this year will take place virtually from Dec. 7-10. Among those who will be eligible for selection: right-hander Santiago Florez (their No. 19 prospect), utility man Kevin Kramer (No. 21), outfielder Lolo Sanchez (No. 23), right-hander Travis MacGregor (No. 30) and lefty Braeden Ogle.

It comes as no surprise that the Pirates chose to add Castro and Kranick to their roster. Even with no Minor League season this year, the club was quite pleased with the work they put in.

• Each team's youngest Top 30 prospect

The Pirates view Castro, their No. 26 prospect, as a potentially valuable super utility-type player. The switch-hitting infielder hit .242/.298/.456 with 19 homers and 73 RBIs over 118 games between Class A Greensboro and Class A Advanced Bradenton as a 20-year-old in 2019. He’s played three infield spots -- second base, third and shortstop -- and continued to work at third and short in Altoona this summer.

During the Pirates’ final series of the season, they added Castro to their traveling taxi squad to let him spend time around the Major League coaching staff.

“Just a talented young player who has a chance to help a team, both on the offensive and defensive side of the game,” Cherington said. “He's certainly got room to grow. He knows he's going to need time in the Minor Leagues.”

The 23-year-old Kranick, an 11th-round Draft pick in 2016, took significant steps forward at the alternate training site. Kranick, the Bucs’ No. 24 prospect, would have spent this season in Double-A after posting a 3.79 ERA and 1.19 WHIP in 20 starts for Bradenton during the '19 season. In the Altoona camp, he flashed a fastball up to 98 mph along with a slider and an improving changeup. Depending on how the Pirates handle this mostly lost year for player development, Kranick could begin next season in Double-A or Triple-A.

“We got to see him a lot and get to know him. He made a pretty significant change early in 2020 to his arm path, his arm pattern. He shortened his arm path and that seemed to really help him both feel better physically and with his stuff,” Cherington said. “A young, big, strong physical guy who we think has a chance to start.”