Not necessarily.
If you only have 6 HGPs, you can only name a 23 man squad; that doesn't stop you having 20 foreign players on the books - but three of them won't be named in the squad. Liverpool had enough overseas players so they could leave the injured VVD off the list. I'm pretty sure we don't have more than 17 overseas players, so we'd have to name, for instance, Dicker to make up the 25 man squad - and still leave Locadia out.
Good info, thanks.