you can also offset the other direction.
for example, this week i was facing CJ and normally would start britt. but needing to be conservative, i reasoned that starting britt would give me too much probabilistic acceleration -- if britt was getting the TDs, it would most likely be at the expense of CJ having a big day... and if CJ went off (which he did), it would be at the expense of the passing game. starting anyone from STL@TEN would stack my gambles, so i needed to look elsewhere.
further, i knew that if CJ did have a big day, i would need to match that with a high upside player. by not playing britt at flex, i was able to take a decent gamble on bush, which paid off just enough to get me my win. yes, britt was projected higher than bush on virtually every website i looked at, but it was a bad way to stack my gambles. by employing good lineup strategy, i was able to bracket that risk by shifting it elsewhere (to NO), much like someone would do in any futures market.
despite the fact that britt was more likely than bush to see his upside, britt's upside profile just didn't match CJ's. so it's not just in shifting the risk (because bush was even less likely to see his upside), but in matching the upside profiles of your insurance policies. even if gambling on bush hadn't panned out, it was still the best move to start him, because doing so put my team in the best position to win. again, FF is essentially a futures market, so all of these basic concepts apply directly... especially in leagues starting D/ST.