Rk: The author's ranking of that pitcher for that day only. Opp: The pitcher's opponent for the day. QR: 'Quality Rating,' or the starting pitcher's matchup rating -- separate from the author's ranking -- which accounts for past history (three years' worth as well as past 21 days), opponent and ballpark. OPS is the primary statistic used in the calculation. Ratings range from 1-10, with 10 representing the best possible matchup, statistically speaking, and 1 representing the worst. So, for example, a 10 is a must-start rating, while a 1 should be avoided (if possible); a 1-2 is poor, 3-4 is fair, 5-6 is average, 7-8 is very good and 9-10 is excellent.