The Reds transferred Santillan (back) to the 60-day injured list Tuesday.

Santillan (back) began core-strengthening exercises this weekend and could be cleared to resume a throwing program within the next week, Bobby Nightengale of The Cincinnati Enquirer reports.

Santillan was placed on the 15-day injured list Friday due to a back injury.

Santillan (0-1) allowed four runs (two earned) on two hits and two walks to blow the save and take the loss Thursday against the Diamondbacks.

Santillan got the save Tuesday after he pitched one inning, giving up one run on three hits while striking out two in Tuesday's 2-1 win over the Red Sox.

Santillan allowed two hits and a walk with two strikeouts in 1.1 innings to earn the save in Saturday's 3-2 win over the Giants.

Santillan earned the save in Thursday's win over the Guardians. He struck out one batter in 1.2 perfect innings.

Santillan struggled in Thursday's loss to the Padres, retiring two batters while hitting two batters, walking another and then giving up a bases-loaded double. A lack of command of his slider was the main culprit for his issues, Mark Sheldon of MLB.com reports. "Right from pitch one, it looked like he was maybe overthrowing his slider a little bit, pulling it," Reds manager David Bell said.

Santillan earned a save against Atlanta on Thursday, pitching a perfect ninth inning during which he struck out two batters.

Santillan is expected to fill a high-leverage middle-innings role this season, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan told Charlie Goldsmith of The Cincinnati Enquirer on Tuesday that he'll serve as a reliever for the Reds to begin the season. "I'll go in and attack every hitter I face," Santillan said.

Santillan is under consideration for one of the three open spots in the Reds' rotation, though he hasn't worked more than two innings in spring training so far, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan (ankle) is scheduled to start Sunday's spring training game against the Giants, Bobby Nightengale of The Cincinnati Enquirer reports.

Santillan underwent ankle surgery during the offseason but has been throwing bullpens to begin spring training, Bobby Nightengale of The Cincinnati Enquirer reports.

Santillan (1-3) allowed one run on one hit with two strikeouts in an inning of work, taking the loss in Saturday's 8-6 defeat to the Pirates. He also hit a batter.

Santillan allowed a solo homer in Saturday's win over the Nationals. The Reds haven't decided what his role will be in 2022 after they moved him to the bullpen this summer, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan was called up by Cincinnati on Tuesday.

Santillan was optioned to Triple-A Louisville on Friday, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan struck out three while allowing one hit over 1.2 innings Monday against the Cubs in relief of starter Wade Miley.

Santillan was recalled by the Reds on Thursday.

Santillan was optioned to Triple-A Louisville on Wednesday.

Santillan (1-2) allowed three runs (two earned) on six hits and two walks while striking out four across three innings to take the loss Tuesday against San Diego.

Santillan (1-1) allowed one earned run on three hits and three walks while striking out eight across six innings, earning the win over Atlanta on Thursday.

Santillan (0-1) pitched only three innings while taking the loss in Friday's defeat to the Padres, allowing three runs on four hits, including two homers. He walked one and struck out three. He was lifted for a pinch hitter in the fourth inning with the Reds trying to tie the game with two outs.

Santillan is scheduled to make his second start Friday against the Padres in San Diego.

Santillan didn't factor into the decision Sunday against the Rockies after giving up one run on five hits and four walks while fanning five across 4.2 innings.

Santillan will start Sunday's game against the Rockies in Cincinnati.

Santillan was recalled by the Reds on Saturday.

Santillan will be called up to start Sunday against the Rockies for his major-league debut, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan is a potential candidate to get a spot start Friday for the Reds against the Cubs, with the team needing a pitcher to fill the gap until Wade Miley returns, Bobby Nightengale of The Cincinnati Enquirer reports.

Santillan will be a part of the Reds' 60-man player pool this season.

Before getting sent down in the first wave of spring training cuts, Santillan pitched in three games, giving up five runs on nine hits and a walk over four innings, good for an 11.25 ERA.

Santillan was added to the Reds' 40-man roster Wednesday.

Santillan will open the year at Double-A Chattanooga, Jonathan Mayo of MLB.com reports.

Santillan was sent to minor-league camp Tuesday, Bobby Nightengale of The Cincinnati Enquirer reports.

Santillan was invited to Cincinnati's major-league spring training camp Wednesday.

Santillan has been dominant at Double-A Pensacola since his promotion, including a 5.2-inning scoreless outing Monday night where he struck out 11 batters, the Reds' official site reports.

Santillan was promoted to Double-A Pensacola on Thursday, Doug Gray of RedsMinorLeagues.com reports.

Santillan gave up one run on six hits and a walk and struck out six over 6.2 innings to pick up the win Sunday for High-A Daytona in the club's 5-1 victory over Dunedin.

Santillan tossed six scoreless innings Wednesday, allowing one hit and two walks while striking out eight for High-A Daytona.

Santillan has thrown 11 consecutive scoreless innings for Low-A Dayton, including five shutout frames Friday against Fort Wayne, where he struck out eight.

Santillan (shoulder) picked up the win in his return from the disabled list Friday, allowing three runs in 6.1 innings pitched while fanning seven and walking just one batter.

Santillan was placed on the 7-day DL on Thursday at Low-A Dayton with shoulder stiffness.

Santillan was promoted to Low-A Dayton earlier last week and was named to the Pioneer League All-Star Game, though he won't participate in that, Better Off Red reports.