It's years ago like, but my work experience from school was spent working with the ground staff at Hillsborough and Middlewood.
They told me that the pitch at Hillsborough is always going to be worse than the training ground because it isn't a natural pitch. It's been put there when the stadium was built, so underneath the turf and drainage etc is the same as you'd find under the road outside.
Whereas the training pitch was a field anyway that they've built facilities around. All they've done, over time, is change the type of grass that's grown on it to make it more hard wearing.
No idea if this means owt from what you say Pulis told you, but that's what the groundsman, at the time, Steve Kiddy, told me.