The number of times 'so-called' Blades fans have written off Billy Sharp (admittedly over a very long period of time, during which he's been farmed out to other clubs) far surpasses the number of times these players (collectively) have been written off thus far, so there's still time for the nay-sayers to be proved wrong.
Anyone who's played football for both shite teams and good teams should have an inkling of what a difference it makes to their own performance (and morale of course). With the influx of youth, energy and class into the Blades squad I have to say that if these much-criticised players don't perform now then there ain't much hope for them in the future!