I think you might be overstating it a little bit. The more I look, the more I think it's the inks that make the biggest difference to the look of the art in these issues, rather than whether it's McFarlane or Capullo's pencils underneath.
For example, this is the first page of issue #23, and I think you could easily mistake it for a McFarlane page. The perspective and lighting in that first panel both take just as many liberties as McFarlane tended to (look at the angles of those walls, and the shadows on Spawn!). I'm not saying it's bad - I like McFarlane's work, as everyone knows - just that it's not that different to McFarlane.
There's less in the way of scratchy detail and overly-fussy linework compared to McFarlane, but again I think that's more down to the inking than anything.
There's still definitely a marked difference compared to the earlier 100%-McFarlane issues though.