Sheen's troubles have mounted in recent weeks after he was hospitalised in January (11) following a wild night of partying with his porn star pals, before undergoing a rehab stint at his Los Angeles home.
A string of scandals have since put his future on TV sitcom Two and a Half Men in doubt - producers axed the show for the rest of the season after he launched a vicious verbal attack on programme creator Chuck Lorre.
Sheen is due to star in the upcoming third installment of the Major League franchise, but he received a stern warning from Morgan Creek Productions CEO James G. Robinson last week (ends27Feb11), demanding he clean up his act or risk losing his role in the picture.
Robinson told TMZ.com he did not want a repeat of the drama he went through with Lindsay Lohan on the set of Georgia Rule, when she failed to show up for work on several occasions.
But filmmaker Ward is confident of Sheen's ability to keep his personal issues separate from his work commitments - and insists he's never seen the actor appear anything but hardworking on set.
Ward tells the New York Post, "Charlie’s a rebel. Maybe he hasn’t seemed as likeable as he usually is, but it’s his persona and people know in their hearts that he’s not a mean guy.
"He has a high tolerance (for drugs and alcohol). I’m concerned anytime I feel like he’s drinking too much or doing drugs, but if there’s anyone who can handle it, it’s him. I’ve never seen him affected professionally by anything he’s done off the set.
"I remember one day when he threw 138 pitches. That’s more than a Major League pitcher throws. And he threw 84 miles an hour. His arm was sore for a week, but he never complained and never stopped.”