Feldman, who turned 34 on Tuesday, was signed to a one-year, $2.3 million contract on Jan. 26, and he is expected to be Cincinnati's No. 4 starter. He was 7-4 with a 3.97 ERA in 40 games (five starts) with the Astros and Blue Jays this past season.
Diaz, 32, has been with the Reds in each of the past three seasons, but he isn't a lock for a bullpen spot this spring. In 45 games in 2016, he had a 3.14 ERA, retired 30 of 45 first batters faced and allowed six of 19 inherited runners to score.
• World Baseball Classic tickets
Herrera, who will turn 23 on March 3, was acquired from the Mets in the Aug. 1 trade for right fielder Jay Bruce. He is currently blocked on Cincinnati's big league roster at second base by Brandon Phillips. During limited big league time with New York in 2014-15, he batted .215 over 49 games, but he hit .274/.335/.456 with 15 homers and 64 RBIs in 110 Triple-A games this past season.
Feldman is part of their Israel's designated pitcher pool (DPP). Each team has the option of using a DPP, which works like this: A team can use up to 10 designated pitchers, but it can't have more than two on its active roster at a time. Those "active" DPs can be replaced at the beginning of each of the next two rounds, but only by another DP. Once a DP has been replaced, he cannot return to the active roster for a subsequent round. Using Team Israel as an example, Shlomo Lipetz and Joey Wagman are the active DPs for the first round of pool play, so they can be replaced on the roster before the second round or the championship round, but only by one of the team's other DPs. And if a DP joins for the second round, he can be replaced for the championship round, but only by another DP.
• Rules for the 2017 WBC
Feldman is not listed as an active DP, so he won't pitch in the first round.
The World Baseball Classic runs from March 6-22. In the U.S., games will air live exclusively in English on MLB Network and on an authenticated basis via MLBNetwork.com/watch, while ESPN Deportes and WatchESPN will provide the exclusive Spanish-language coverage. MLB.TV Premium subscribers in the U.S. will have access to watch every tournament game live on any of the streaming service's 400-plus supported devices. Internationally, the tournament will be distributed across all forms of television, internet, mobile and radio in territories excluding the U.S., Puerto Rico and Japan. Get tickets for games at Marlins Park, Tokyo Dome, Gocheok Sky Dome in Seoul, Estadio Charros de Jalisco in Mexico, Petco Park, as well as the Championship Round at Dodger Stadium, while complete coverage -- including schedules, video, stats and gear -- is available at WorldBaseballClassic.com.