Pearson may begin the season on the disabled list after sustaining a Grade 1 strain of his right groin in his spring debut.
Analysis: Pearson, considered one of the majors' top pitching prospects, had been viewed as a serious candidate to open the season as part of Toronto's rotation. He still could be ready to go sometime in April as long as the injury isn't too severe.
The Nationals announced that Lester will undergo surgery to have his thyroid gland removed.
Analysis: Nationals manager Dave Martinez said he's hopeful that Lester will be able to pitch in about a week and remains optimistic that the 37-year-old will be ready for the start of the season. Lester looks to be slotted into the No. 4 spot in Washington's rotation behind Max Scherzer, Stephen Strasburg and Patrick Corbin.
Calhoun underwent successful surgery to repair a torn meniscus in his right knee, but he's unlikely to be ready for Arizona's season opener.
Analysis: Calhoun is likely facing a 4-to-6 week recovery but barring any setbacks, should be back sometime in April. Youngster Daulton Varsho may begin the season as the Diamondbacks' regular right fielder.
Valdez (fractured left ring finger) has been recommended to undergo surgery that would likely sideline him the entire season, according to MLB Network. The left-hander will seek a second opinion before he and the Astros make a final decision.
Analysis: Even if he avoids surgery, Valdez will likely be sidelined into at least May as his finger heals. The 27-year-old had been ticketed to be a key part of the Astros' rotation after going 5-3 with a 3.57 ERA and a team-best 76 strikeouts in 70 2/3 innings last season.
Desmond is opting out for a second straight season. Desmond announced Sunday on his Instagram account that his ''desire to be with my family is greater than my desire to go back and play baseball under these circumstances. I'm going to train and watch how things unfold.'' He added ''for now'' in his statement to opt out, leaving the door open for a possible return.
Analysis: The 35-year-old Desmond is in the final year of a five-year, $70 million deal he signed in December 2016. He is scheduled to make $8 million this season. Colorado has a $15 million option for 2022 with a $2 million buyout. Desmond is a career .263 hitter with 181 homers and 711 RBIs over an 11-year career with Washington, Texas and Colorado. He batted .255 with 20 homers in 140 games with Colorado in 2019.
Realmuto will miss at least the first two weeks of spring training after being diagnosed with a small fracture of his right thumb.
Analysis: Both the Phillies and Realmuto remain confident that he'll be ready in time for the team's April 1 opener against Atlanta. The two-time All-Star signed a five-year, $115.5 million contract to stay with Philadelphia in January.