You're right there are no guarantees, but as is too often you engage in gross hyperbole.
They didn't "throw away" a potential playoff spot last year. They traded away two guys at high value, who both immediately cratered, and actually played better after the deadline deals.
Now, I'm not saying sit on your hands and do nothing. But I am saying they should not be maximizing wins this year to the detriment of wins in future years, and many of these FA contracts recently handed out are going to do exactly that.