last year, detroit's starting pitchers had the lowest ERA, and kansas city's had the highest, at 4.00 and 5.85, respectively. last year, the minnesota twins' re leviers had the lowest ERA, and kansas city's had the highest, at 2.91 and 5.36, respectively. detroit's relievers pitched to a 3.51 ERA. last year, only four teams had bullpen ERA's higher than that of their starters - cleveland, florida, milwaukee, and san francisco. across the majors, starters had an ERA of 4.69, while releivers had an ERA of 4.20 if you can routinely get better performances out of your relievers, why would you pitch your starters more often? ...also, i think it has a lot to do with coaches and players becoming ever so much more risk-averse, and therefore continually cutting down on potential overuse, regardless of whether or not a specific pitcher can actually handle the use. the reward of finding a true innings eater who can go out and throw 300 innings is no longer, i guess, worth the risk of chewing up and spitting out all the otherwise fine pitchers who cannot. (if i knew where to get league- or team- data for past years that was split out into starters and relievers, i'd be more than happy to do the same for 1969 and such, but i don't, so i won't.)