The logic goes something like this:
(1) The Royals run differential last year suggested a 78 win team.
(2) Projections expect large amounts of regression from players like Gordon and Francoeur, but Rany believes their success in 2011 is at least partially attributable to real and sustainable adjustments (Seitzer!), and regression won't be as steep as projected.
(3) The Royals are very young and should be expected to improve over last year
(4) The rotation won't hurt the team as much as a lot of people expect, both because (a) it won't be quite as bad as people expect and (b) given the expanding role of the bullpen and the importance of defense, the starting rotation isn't responsibe for as large a share of run prevention as conventional wisdom holds.
There's no calculation at the end that outputs 81 wins, so the numbers guys won't be satisfied, but it's not a totally unreasonable argument.