Each day, posted near the lineup card in clubhouses, is a bare-essentials scouting report of the opposing pitcher. Last Saturday, in the Red Sox clubhouse in New York, for example, the advance data on Shawn Chacon suggested that the Sox should expect the following: fastball, cutter, slider, changeup, curveball. The two other well-known pitch types are the splitter and the knuckleball. But there are variations on of the above pitches. The Globe asked Sox pitching coach Dave Wallace to explain all of these pitches.