Earl Weaver's Seventh Law: It's easier to find four good starters than five. Probably other of his contemporaries did this too, but Earl used 4 main starters, then would use an occasional spot start from a long man in the bullpen, or a young kid he was breaking into the rotation. For example, the 1978 team used a rotation of Palmer, Flanagan, Dennis Martinez, and Scot MacGregor, each starting between 35-40 games. Then Nelson Briles made 8 starts, and Joe Kerrigan made 2. I find this to be a brilliant strategy. The season is roughly 6 months long. That's 182 days to play 162 games. That means 20 off days built into the schedule. Add in the 10 starts by random mop up guys, like Earl did in 1978, and that leaves your 4 starters to pitch 152 games over 182 days. That leaves 30 off days for the 4 man rotation, or about one day off every 5 days. So a manager who actually plans ahead could go with a 4 man rotation and still have each start only every 5 days. Your best 4 pitchers would get about 38 starts in a year.