yeah i agree, saves are probably the scrappiest stat in standard 5x5 roto. even bad closers can give you save #s, and i see it like, you ride the closers you have for as long as you have... if you've got two closers early on you try whatever you can to get anothger closer or two, hopefully having excess SP or offense to trade for it.
if you're on the flipside and you've got like more than 4 closers, i think one strategy is to ride them out for as long as you can, get a big chunk of save #s, then trade some of them to people who are more desperate for them as the season wears onward.
edit: the only reason i'd drop a closer is if they're not going to have a lot of ops, or if they're going to lose the job. for example last year i dropped kelvim escobar to pick up this kid dontrelle willis who was just about to pwn the reds for the 2nd consecutive start. the rest is history.