Good article
here on Halladay.
On the mound, though, he could not have looked less like the virtuoso at ease. It took only a glimpse to know that Halladay was a worker above all else, that his success was no mere unspooling of innate talent. His manipulation of the baseball impressed—fastballs cutting or tailing, curveballs dipping subtly or biting hard—and he had a classic pitcher’s build, but his core gift was for focusing on the moment-by-moment labor of tallying outs. He wore a stoic expression and used a simple, repeatable delivery; he rarely celebrated or complained. He was the competitive ideal, a player who offered only his best, whatever the circumstance.
Fans outside Toronto might not remember this, but Doc struggled mightily early in his career (go to the draft center and do a search for the pitcher with at least 50 IP who has the highest ERA ever -- you'll be surprised). He went down to the minors and really worked his butt off to become what he was. I think that work ethic, and that fear of failure, stayed with him his entire career. I saw most of his starts in Toronto, and he gave it his all every single time.