DL for everyday guys for various ailments, including pulling a hamstring or twisting an ankle...now that's worthwhile rest. But pitchers arms/shoulders....the guy is throwing 99...hell, expect to be sore. But when Catfish Hunter, Fergie Jenkins, Luis Tiant, Tom Seaver, Nolan Ryan, etc. threw 250 to 300 innings, no one batted an eye. Ask them how sore they were between starts, how many times their arms felt really sore, shoulders aching, etc....it's part of the game. It did not cause injuries. Having the 4 to 5 days between starts was the "rest." Over throwing in MLB is over-rated. Except in one case---which is throwing relievers 5x a week and not expecting effectivenss to decrease. So many teams coddle the starter and yet treat the reliever like they are indestructable. Anyway, it's wrong both ways. Limit relievers more and let SPs go longer, but then that affects also the money structure and salaries for relievers. The need for 4 to 5 guys in a 9-inning game, situational yes, but in the overall...not necessary.