You'll need more than zdata to rotate the plot. You'll need to define the x and y positions of the points.
If you just want to rotate the plot, you can just use rotate(). It's up to you to pick the view position you want.
[x y z] = peaks(20);
theta = 15;
hs = mesh(x,y,z);
axis equal
% pick some view vector
% [0 1 0] rotation vector is || to y-axis
% [-3 0 0] origin of rotation vector
rotate(hs,[0 1 0],-theta,[-3 0 0])
view([0 -1 0]) % set the view
axis equal
xlabel('x')
% get the rotated data
xr = hs.XData;
yr = hs.YData;
zr = hs.ZData;
