Shaikh, I think, accounts for the variability of prices by emphasizing that the tendency of the rate of profit to fall and the rising organic composition derive from rising real wages. (Or he claims that that is Dobb's idea.) He raises the argument that technical improvements will be made by capitalists only if they know the wage rise will not offset productivity increases, but doesn't take that argument very seriously, since such foresight is what competition excludes.
Christian