I agree I just don't think Krejci is effective anymore, I think he could be a great third line center because of his smarts and defense but I don't picture him as a number 2 center on a contender. They need a younger, faster option there or if they are going to go for it this year then get an impact second line center for this year and maybe next.
JFK certainly doesn't appear to be a second line option or a third at this point, Frederic may take more than a year in the minors to be ready and Studnicka may well be in the same boat of needing more time to adjust to the pro game from juniors next year.
They should really drop Krecji a line and then Backes, this makes you very strong down the middle with a projected very good second line center taking Krejci's spot.
Donato, Heinen, Bjork and JFK should be dangled to get that player in here, all of them are expendable for the right player (not all in one trade unless it's a new number one center). The Senyshyn's, Zboril's and other prospects who look like busts at this point can be added if someone sees value in them.