The A’s promising young starting pitchers will have a tremendous resource at their disposal this spring: Dave Stewart, one of the most intimidating pitchers in modern baseball, will be a guest instructor for the team, he told The Chronicle on Friday.

Stewart, 60, was a ferocious competitor who had four consecutive 20-plus win seasons for the A’s from 1987-90 and went 119-78 with a 3.73 ERA in his eight years with the team. He thrived in the postseason, going 10-6 with a 2.77 ERA, and he was the MVP of the 1989 World Series as well as the ALCS MVP in both 1990 and 1993.

“He’s one of the all-time A’s greats,” manager Bob Melvin said via text. “I want him to emphasize what it takes to be a great competitor, leader and team player.”

Oakland’s rebuilding efforts center around the team’s core of young players, including starters A.J. Puk, 22, the A’s top pick in the 2016 draft, and Logan Shore, 23, the second-round pick that same year.

“Whatever they want me to do, I’ll do - if they want me to work with Puk or Jharel Cotton or Sean Manaea, I’m just there to help any way I can,” said Stewart, who will be in camp Feb 14-18. “I just want to bring them value.”

Is it possible to instill intimidation or intensity? “You’re either intimidating or you’re not,” Stewart said. “I don’t think you can teach it. If I had a family member in the batter’s box, I’d knock them in the dirt if I had to. You have to have that kind of mentality to get the job done.”

Stewart still has it: At last week’s Coaching Corps Game Changers awards, he flashed his trademark death stare when called upon.

Stewart, who was born and raised in Oakland, has enjoyed an unusual post-baseball career, serving as a pitching coach; a player agent and a front-office executive, including two years as Arizona’s general manager. He is now an analyst on the A’s pre- and post game TV broadcasts, and he recently was part of a group, headed up by Tagg Romney and Jeb Bush, that made a failed bid to by the Miami Marlins.

Stewart is the first former A’s pitcher to be a special guest instructor since his friend and former teammate, the late Bob Welch, did so in 2013-14. Oakland’s other guest instructors during the spring are former A’s first baseman Scott Hatteberg and second baseman Mark Ellis. Hall of Famer outfielder Rickey Henderson serves as a guest instructor during the spring and also during the regular season.

Susan Slusser is a San Francisco Chronicle staff writer. Email: sslusser@sfchronicle.com Twitter: @susanslusser