If the Mets have done nothing else right over the last few seasons, they did the right thing with the way they’ve managed Matt Harvey—by, as I said before, letting him pitch. Contrast that with the blunders made by the Yankees with their two hard-throwing right-handers, Joba Chamberlain and Phil Hughes. Towards the end of the 2007 season, the Yankees brought Chamberlain up and let him throw fastballs and hard sliders for 24 innings; he was practically unhittable, posting an ERA 0.38. The next season, anxious to protect their ace, they imposed a series of “Joba rules,” limiting how many pitches he could throw in any one outing and also limiting the number of his appearances.
via How Matt Harvey Became the Most Exciting Pitcher in Baseball – Allen Barra – The Atlantic.